Sentinel Passages - The Fountain, Trench and The Cove (Caverns 16-18) - IdleOn

Sentinel Passages is a new set of caverns you can find at The Hole in World 5 of IdleOn. These caverns include The Fountain, The Bottomless Trench and The Cove, which all come with brand new mechanics and bonuses for you to work on.

• The Fountain - Cavern 16
• The Bottomless Trench - Cavern 17
• The Cove / The Lair - Cavern 18

In order to access Sentinel Passages caverns, you need to get your Explorer to Level 16+. 

The introduction of Sentinel Passages also added some brand new Engineer Upgrades that can boost these caverns.

You can find previous caverns (1-15) at our The Caverns guide.

The Fountain - Cavern 16

The Fountain is a place where you can stand / do nothing to help fill up the magical fountain that produces different types of coins. You can then use these coins to upgrade various bonuses, including account-wide bonuses.

If you click on The Fountain, you'll see several upgrades and various bars that fill up. Each time the Fountain fills up, it produces one random coin that you have available. Through the various upgrades, you can unlock new coin types and different fountain bars that fill up over time.

Once you unlock the final upgrade of the normal water page, you'll be given the option to "Change Water". This doesn't actually change anything other than showing you new upgrades you can invest in.

You'll also unlock the Marble Gauge; when this fills up you are granted a certain amount of Marbles. Marbles can be used to upgrade every existing upgrade at The Fountain that gives a Multiply Bonus.

The final Fountain bar is unlocked through Rubber Ducky; when this fills up, it gives you a chance of finding a Rubber Duck that appears on your Fountain, multiplying your currency gains per duck found.

Two important mechanics to remember:

• Turn and Push - This allows you to select any currency you have unlocked and ignore it so that your fountain doesn't create it. This means you can focus on one particular currency at a time to get their upgrades.
• Royal Stacks - Royal Stacks boost the value of coins when you collect them; a Royal Stack has a massive multiplier so you should only collect your coins once they have a Royal Crown icon on top of them
• Greatest Desire - Similar to Turn and Push, if you click on a currency you can turn it into a "Desire" coin, which makes them worth more when you collect them (a huge multiplier!)

Ideally you should produce one coin-type at a time, desire it and only collect it once it has the Royal Stack icon. You'll get the most coins then.

If you don't actively-AFK at The Fountain, you'll still get some coin generation going on but it is incredibly slow compared to being active-afk.

The Fountain Upgrades

You can purchase the following upgrades at The Fountain

Upgrade	Desc	Cost Type
Yellow Water	Unlock Yellow Water. Tap the Change Water button to toggle which water the Fountain is using. Also, x Currency Value
Currency Booster I	All currencies are worth +% more. Currencies are ALL money types here at the Fountain, from coins to dollars and more!
Penny Lane	Increases the value of Bronze Coins. All bronze coins you find have a base value of x Your total Currency multi: ^ (Affects value of all Fountain money)
Nickel and Diming	You can now find Silver Coins. All silver coins you find have a base value of x
Dubloon Desires	You can now find Golden Coins. All golden coins you find have a base value of x
Stackin' Silver	Silver coins are worth x more.
Stackin' Gold	Golden coins are worth x more.
Stackin' Dollars	Dollar Bills are worth x more.
Money Back Guarantee	Currency generated while at maximum capacity aren't wasted, and instead auto collected at x% of their value.
Fountain Filling	Every time the fountain fills up, it creates a new coin. This will happen in x From empty, it takes: # to fill
Extra Space	Coins can appear in x different areas on the ground. This means your current max coin capacity is # coins
Taller Stacks	Each area can stack up to x coins, this upgrade increases it by +. This means your current max coin capacity is # coins
Water Bender	The fountain fills up xx faster while you are actively standing in this cavern specifically.
Monumental Boost	All Bravery Monument bonuses are x larger.
Cosmological Boost	Cosmo the Villager gains x more EXP than normal.
Golden Bucket Boost	Your 1st bucket at The Well cavern is golden. Golden buckets have x fill rate.
Class EXP Boost	Boosts Class EXP gain by x
Treasure Boost	All Sailing Chests you open contain x more Treasure to upgrade your Boats with!
Orion Boost	Permanently boost Feather Generation rate at Orion the Horned Owl by x
Mythril Transience	Bronze, silver, and gold coins are worth +% more per POW 10 Mythril you have, over at The Well cavern. Total Bonus:xx
Green Water	Unlock Green Water. Also, x Currency Value.
Currency Booster II	All currencies are worth +% more.
Dolla Dolla Bills	You can now find Dollar Bills. All dollar bills you find have a base value of x
Credit Swisse	You can now find Credit Bills. All credit bills you find have a base value of x
In Gov We Trust	You can now find Treasury Bills. All treasury bills you find have a base value of x
Stackin' Creds	Credit bills are worth x more.
Stackin' T-Bills	Treasury bills are worth x more.
Stackin' Monayy	Moolah Stacks are worth x more.
Royal Stacks	There's a 1 in x chance for a currency stack to become 'royal' when the fountain fills. All coins in a royal stack are worth more.
Regal Riches	Royal stacks are worth xx more, to be specific.
Marble Filling	Adds a new fountain bar, which when filled creates x marble. Spend these on upgrades to multiply their bonuses via Marbleization.
Greatest Desire	You can now click and HOLD on a currency at the top of the screen to DESIRE it, making them worth x more when collected.
Turn and Push	You can now click a currency at the top to IGNORE it, so it's never created. Click again to undo this at any time. Also, +% all currency
Judicial Boost	All Justice Monument bonuses are x larger.
Skim Reading	Boost the Study Rate for Bolaia the Villager by x
Fine Tuning	All your Harp Strings gain x more exp than normal
Swingy O' Sword	Boosts Damage for all characters by x
Summoneer	All Summoning Essence generation is x greater than before
Better Poppy	Permanently boost Fish Generation rate at Poppy the Kangaroo Mouse by x
Sharp Surrogate	Dollar, Credit, and Treasury bills are worth +% more per POW 10 Sharp Notes you have, over at The Harp cavern. Total Bonus:xx
Red Water	Unlock Red Water... well, it will in the future. Also, x Currency Value, at least THAT'S here in the present!
Currency Booster III	All currencies are worth +% more.
Moolahleluja	You can now find Moolah Stacks. All moolah stacks you find have a base value of x, but only get 鉢(Total Currency Multi) which is: ^
Shillin Grillin	You can now find Shilling Stacks. All shilling stacks you find have a base value of x, but only get 鉢(Total Currency Multi) which is: ^
Rob Greane	You can now find Greane Stacks. All greane stacks you find have a base value of x, but only get 鉢(Total Currency Multi) which is: ^
Stackin' Shillin	Shilling Stacks are worth x more.
Stackin' Gbacks	Greane Stacks are worth x more.
Stackin' Funds	Oldmoney Stacks are worth x more.
Luck fo' REAL	All currencies collected have a 1 in x of being LUCKY, multiplying the value of that currency type forever! Each additional one is 4x rarer
Skilluck	Boosts bonus of each LUCKY coin to +x%. Also, you can see how many LUCKY coins of each type you have from the number of dots above them.
Lucky Ducky	Boost Rubber Ducky chance and LUCKY coin chance by +%
Ducktactular	Your Rubber Duckies each boost the value of all coins you find by x. Total Ducky Bonus: xx
Rubber Ducky	Adds a new fountain bar, which when filled has a 1 in x chance of giving +1 Rubber Ducky stack.
Wisdom Boost	All Wisdom Monument bonuses are x larger.
Minaus Costs	Minau the Villager's upgrades all are x cheaper than before
Enchanterest	Your Enchant chance over at The Jar cavern is x larger than before
Pen N Paper	Boosts Research EXP gain by x
Cook Maxxing	Boosts Cooking Mastery EXP gain by x. Note that Cooking Mastery is unlocked at Rift 61.
Bubba Forever	Permanently boost Meat Slice Production rate at Bubba the Seal by x
Rupie Monie	Moolah, Shilling, and Greane stacks are worth +% more per POW 10 basic Red Rupie you have, over at The Jar cavern.

The Fountain Boosts

You can boost The Fountain from these other mechanics:

Upgrade	Bonus	From
Triple Decker Extender	All coinstacks at The Fountain can stack +3 coins higher than before!	The Engineer (The Hole)
Trench ~ Coin Synergy	Boosts the value of all coin types, also called Currencies, by 1.10x per Trench Depth you've cast!	The Engineer (The Hole)
Size DOES Matter	When collecting a coinstack at The Fountain, you get +10% MULTI per stack height. Example:If a stack was 5 coins high, they'd all be worth 1.50x more!!!	The Engineer (The Hole)
	You can Marbleize upgrades more than once! Also, x higher Marble production!	Study Bolaia (The Hole)

The Bottomless Trench - Cavern 17

The Bottomless Trench is a Skilling cavern that requires you to Fish! You need to use your Fishing skill to break through each Depth.

You'll find each Trench Depth requires more and more Fishing Efficiency to be able to catch the Fish, as well as more required Fish to get.

You'll get 1 Opal per Depth cleared and you can also AFK on your IdleOn characters here.

You can earn the following bonuses from The Bottomless Trench:

Upgrade	Bonus	From
Trench ~ Coin Synergy	Boosts the value of all coin types, also called Currencies, by 1.10x per Trench Depth you've cast!	The Engineer (The Hole)
Trench Trickledown	+15% All Skill Efficiency, and +10% All Skill EXP gain per Bottomless Trench Depth you've cast down to!	The Engineer (The Hole)
	Every depth cast lowers the resources needed to destroy other skilling caverns by 5%	Study Bolaia (The Hole)

The Cove / The Lair - Cavern 18

The Cove (also referred to as The Lair) is where special Crystal Glunko mobs spawn that drop various Crystals that you can collect. You can then spend these crystals on upgrades at The Cove.

The Cove also removes all your Drop Rate, Multikill, Respawn Rate and AFK Gains. You have to increase these stats through The Cove upgrades.

There are two sets of upgrades: Crystals and Jewels. A Crystal Glunko can drop both types of these.

For this Cavern, you'll want to use a character that has good respawn mechanics so that you can constantly be killing them:

• Windwalker
• Siege Breaker (Best)

The Siege Breaker has a Talent called Pirate Flag, which allows it to spawn Plunderous Mobs, which give massive EXP and Drop rate boosts, allowing you to get more Crystals.

You can also click on a Crystal type in The Cove Upgrades menu so that it is "specified", boosting it's drop rate even more. You can do this for one Crystal and One Jewel.

You can also boost AFK rates so that your characters can AFK at The Cove; however, you're still likely to get more resources by actively killing mobs.

The Cove Upgrades

The following upgrades are available at The Cove:

Upgrade	Bonus	Crystal
Opal Find	Get +1 Opal to invest into Villagers!
Slop Drop	Boost Drop Rate here in The Cove by %
Reslime	Increase Crystal Glunko respawn rate by %
Droplier	Multiply Drop Rate here in this Cove by x
Killionaire	+% DR here in The Cave per POW 10 Glunko kills
Insta-Ribbon	Get a rank 15 Ribbon for Cooking, instantly!
Big Hit Multikill	Boost your Multikill Per Dmg Tier here to %
Active Drops	Decrease the cost of all upgrades here by %
Sleepy Drops	Boost AFK Gains rate here by %
One Big Blue	x Drop Value for your Specified blue Shape
Blue Collector	% DR here, per digit of Blue Shapes owned
Researchy	x Research EXP gain for outside this cove
Droplier+	Multiply Drop Rate here in this Cove by x
Sleepy Drops+	Boost AFK Gains rates here by %
Cavernicus	Earn x more resources from all caverns
Multikill	Boost base Multikill here by %
One Big Purp	x Drop Value for your specified purp shape
Slop Drop+	Boost Drop Rate here by %
Rich Get Rich	Boost DR here by % per POW 10 normal DR
DeEmGe	Boost Total Damage for all chars by x
Grandioso	Boost Grand Discovery Chance in Spelunking by x
Slop Drop++	Boost Drop Rate here in Cavern 18 by %
Purp Collector	+% DR here, per digit of Purp Shapes owned
IDK Broh	World 7 Skill 3 my man, not yet.

The Cove Boosts

You can find the following boosts that help The Cove:

Upgrade	Bonus	From
Glunko Conglomeration	Crystal Glunko monsters in Cavern 18 now respawn 25% faster!	The Engineer (The Hole)
More Goo	Whenever you pick up shapes dropped by Crystal Glunko monsters, there's a 10% chance to get DOUBLE the amount!	The Engineer (The Hole)
Even More Goo	Boosts your Double Shape chance from 10% up to 20%	The Engineer (The Hole)
Profoun-Tain	Each level gives +1 Max Coin Stack size, 1.25x all coins value, and 1.10 Marble rate for The Fountain cave!	Hole Majik (The Hole)
Measure	+% Fountain Coin Value	Measure (The Hole)
	The first x upgrades each day in The Cove are 15% cheaper	Study Bolaia (The Hole)