Sentry Expert is the Engineer Monkey's path 1 tier 4 upgrade in Bloons TD 6. It replaces its Sentries with four different types of Sentries that each have a different attack. It can spawn Crushing Sentries, Boom Sentries, Cold Sentries, and Energy Sentries, and it spawns them in that order by default, but it can prioritize or skip Sentries depending on what Bloons are currently on-screen.
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Usually, the Sentry Expert spawns Crushing, Boom, Cold, and Energy Sentries in that order. However, some sentries are skipped if certain Bloons appear on screen, and conversely some sentries are prioritized.
Sentries get the following benefits from crosspathing:
The Crushing Sentry fires spiked balls every 1.2 seconds that can bounce off blockers, similarly to Spike-o-pult; however, they'll not rehit Bloons after bouncing off obstacles. Each spiked ball can pop up to 22 Bloons per shot (33 with Oversize Nails). It deals 2 damage, +4 to Ceramic Bloons, and has the Shatter damage type (can pop frozen Bloons but not Lead Bloons).
Boom Sentry
The Boom Sentry fires bombs every second that explode on contact. Its explosion has 18 radius, dealing 4 damage and can pop up to 30 Bloons (45 with Oversize Nails). Explosions pop frozen Bloons and Lead Bloons, but not Black Bloons.
Cold Sentry
The Cold Sentry fires ice bombs every 1.5 seconds that explode on contact, similar to Cryo Cannon. Its explosion has 18 radius, dealing 1 damage and freezes up to 24 Bloons (36 with Oversize Nails) for 1.5 seconds, and inflicts Permafrost (50% slowdown for infinite duration). Both the freeze and Permafrost effects soak up to 2 layers. It does not damage or freeze White Bloons, Lead Bloons, frozen Bloons, or MOAB-Class Bloons, and will never target MOAB-class Bloons.
Energy Sentry
The Energy Sentry fires lasers every 0.57 seconds. It deals 2 damage, +2 to MOAB-Class Bloons, and can pop 8 bloons (12 with Oversize Nails). It can damage frozen Bloons, but not Lead Bloons or Purple Bloons. Compared to other specialized sentries, its lasers have the fastest projectile speed (280 units/second), but still slower than the main nailgun.
Sentry Expert is a decent mid-game DPS with its variety of sentry types handling Bloons all around, but its sentry spawning algorithm can be unreliable and struggles on rounds where spawned Bloons change faster than Sentry Expert can redeploy sentries (e.g. rounds 50 and 53); stalling towers like MOAB Shove can counter this weakness.
4-2-0's damage bonuses are helpful and is preferred if building into Sentry Champion. 4-0-2 can be beneficial for Sentry Expert in the mid-game due to its significant pierce bonus, in addition to Pin helping stop Rainbow Bloons and below.
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Continuing our efforts to make crosspaths meaningful and fit the style of each path more solidly, a number of crosspath and base level balance shifts were made. — Update notes
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Sentry: Spawn rate increased ― 7s → 6s
Range of all Sentry types increased ― 45 → 50
4-1-0, 4-2-0
Larger Service Area now grants +4 range to Sentries
4-0-1, 4-0-2
Oversize Nails now allows Sentries to pop frozen Bloons
It has been clear that Sentry Expert needs changes, with Cryo sentries the only ones that really seemed valuable and purposeful, so all of the others have been improved to fit their role. Additionally higher tier sentries will now be able to benefit from the xx2 Pin crosspath, so enjoy some laser pins. — Update notes
Sentry Expert really needed some logic fixes to get more of the actual correct sentries placed at the right times, it has also received a number of power buffs across the board to the special sentries at T4 complimenting the new logic reworking. — Update notes
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Sentry Expert logic has been reworked to evaluate threat levels based on Bloon types that it can counter, Bloon types that counter the sentries that it wants to spawn, and which of the current threats on screen is the greatest. Distribution of sentry types should scale based on how much one Bloon threat is more of a threat than another.
Crushing Sentry: Damage to Ceramics increased ― +1 → +4
Crushing Sentry: Damage type changed ― Sharp → Shatter
The MOAB offense of top path lacks for a mainly dps tower that is quite complex to use, T3 Sprockets already feels underwhelming so is seeing a buff here carrying up to T4, and the 320 crosspath will now be able to double dip on the Fortified & MOAB damage bonuses that it gains. — Update notes
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Main attack: Attack cooldown reduced ― 0.42s → 0.35s (attack speed increased by 20%)
4-2-0
Sentry: Deconstruction's bonus damage to MOAB-Class Bloons and Fortified Bloons are no longer mutually exclusive
Improvements for Sentry Expert AI based on your feedback. — Update notes
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Sentry spawner: Priority given to Cold Sentries based on the number of Pinks now caps at 20 Pinks; reaching this threshold gives more priority to balancing the number of Cold Sentries and Boom Sentries
Sentry spawner: Priority given to Energy Sentries based on the number of blue MOABs now caps at 10 blue MOABs; reaching this threshold gives more priority to balancing the number of Crushing Sentries and Cold Sentries
Sentry placements are slightly changing to improve their reliability, and will now spawn closer to the track depending on how much range the sentry has. — Update notes
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Overall cost reduced by $50 (due to cost changes for previous tiers)
Sentry deployment: Sentries now spawn within 20% of their range to the track
This was becoming annoying screen clutter with large numbers of sentries, and feels unnecessary when you can overclock the engineer itself to create more sentries instead. — Update notes
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Overclock and Ultraboost abilities no longer target Engineer sentries
Really only one major change here; a rebalancing to how the 2xx Crosspath applies across various engineer upgrades, and some base stats being changed to accommodate fitting this. — Update notes
Sentries deploy with different damage types based on your need.
Crushing Sentry: Attack cooldown reduced ― 1.25s → 1s (attack speed increased by 25%)
Sentry: No longer gains Camo detection after loading a save (bug fix)
Sentry Expert logic has been reworked to evaluate threat levels based on Bloon types that it can counter, Bloon types that counter the sentries that it wants to spawn, and which of the current threats on screen is the greatest. Distribution of sentry types should scale based on how much one Bloon threat is more of a threat than another.
Sentry Expert with 400 crosspath
Sentry Expert with 410 crosspath
Sentry Expert with 420 crosspath
Sentry Expert with 401 crosspath
Sentry Expert with 402 crosspath
Boom Sentry attacking
Energy Sentry attacking
Cold Sentry attacking
Crushing Sentry attacking
Portrait
Crushing Sentry portrait
Boom Sentry portrait
Cold Sentry portrait
Energy Sentry portrait
Upgrade icon
Insta Monkey icon
Crushing Sentry
Boom Sentry
Cold Sentry
Energy Sentry
