How to Beat Test Subject in Slay The Spire 2

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Slay The Spire 2 is now available, bringing with it a new set of incredibly tough bosses. Get ready to be defeated repeatedly… unless you build a powerful deck that lets you do the defeating!

The last three bosses you’ll encounter at the top of the Spire, finishing Act 3, are incredibly difficult. One of these is the Test Subject, and it will really push your defenses and how quickly you can defeat enemies!

Let’s break down what makes this fight special and discuss the most effective strategies for defeating this enemy!

Encounter Mechanics

You’ll quickly notice that the Test Subject has a unique feature: every time you defeat its head, a new one grows back with an extra 100 health. This happens twice during the fight, so you’ll need to inflict a total of 600 damage to completely defeat it.

It doesn’t sound too difficult at first, does it? However, that’s not all there is to it. This enemy has multiple stages, and each one gives it a special boost:

  • In phase 1, the Test Subject will have Enrage, giving it +2 Strength every time you cast a skill.
  • Phase 2 has Painful Stabs, which inflicts a wound every time the Test Subject deals unblocked damage.
  • Phase 3 has Intangible every other turn. Monsters with intangible will only take 1 damage at a time. You might remember this mechanic from the Nemesis in Slay the Spire 1.

The first two stages are fairly straightforward, but the third one is much more challenging. This mechanic, which makes the enemy shift between tangible and intangible states, effectively doubles the length of this phase. You’ll do very little damage on many turns, so you need to be able to deal a lot of damage quickly when the enemy is vulnerable, and have strong defenses to survive when it’s not.

Boss Strategies

Before discussing effective strategies, it’s important to know that some decks may find this boss challenging. Decks focused on stacking negative effects, such as Poison or Doom, aren’t ideal, as they perform best against enemies with a lot of health but less defense.

When the Test Subject moves to a new phase, any negative effects you’ve applied to it will be removed, so you’ll have to reapply them.

It’s best to focus on a very defensive strategy for this battle, as it can be quite lengthy. Skills like Frost Orbs, Barricade, Afterimage, and Reanimate, along with other defensive abilities, will be very helpful.

Keep an eye out for powerful relics from the Ancients! Items like the Jewelled Mask, Storybook, and Jewellery Box can significantly strengthen your deck.

If you prefer to focus on offense rather than defense, powerful attack builds work really well. Builds that get stronger over time are also a good choice! Players using Demon Form Ironclads or Sovereign Blade Regents should be able to handle this easily.

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If you combine these strategies with reliable damage output and good energy production, you’ll be able to quickly overcome each challenge before it becomes dangerous. The key is dealing a lot of damage all at once.

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2026-03-08 22:09