How to unlock Act 4 in Slay the Spire

Learn how to unlock Act 4 and go head to head with the toughest bosses in Slay the Spire.


Slay the Spire challenges players to complete a series of dungeons, defeating bosses and exploring different paths as they progress. Late last year the developers added a new act to the game, giving players the ultimate challenge. If you’re trying to unlock Act 4, then you’re going to need to be ready to put in quite a bit of work.

How to Unlock Act 4

In order to unlock Act 4 you’re going to need to first “win” the game by defeating the Act 3 boss with all of the game’s characters. This task might take you a bit, but once you complete it, start a new run of the game with any character.

You should notice a small symbol next to your name now. This is where the various keys that you need to acquire to unlock Act 4 will go. There are three keys that you need to find and acquire; the Ruby Key, the Sapphire Key and the Emerald Key.

Obtaining the three different keys will be the most difficult portion of this run. Unlike the fragments, which are unlocked by beating the Act 3 boss on each character, you’ll need to find the keys each time you want to make the run into Act 4, so knowing how to find them effectively will be key to your success in this endeavor.

Slay the Spire in-game deck and battle
Players use a deck of cards to battle in Slay the Spire.

To find the first key, the Ruby Key, you’re going to need to make your way to a resting place and look out for the “Recall” option. Using this will allow you to acquire the Ruby Key and add it to your inventory.

Next up is the Sapphire Key. This key can only be found inside of a chest, which means you’re going to need to explore the map until you happen across it, as the chest’s location can change with each run.

Finally, the last key, the Emerald Key, can be found by fighting and defeating a “marked” Elite enemy. Completing the fight will reward you with the usual trinkets, as well as the Emerald Key.

With all three keys, you’ll gain access to Act 4, which only contains one main path and two dangerous boss fights. We’ll have more content for Slay the Spire coming shortly, so make sure you head back over to our Slay the Spire home page for the latest strategies and in-depth content.

Guides Editor

Joshua holds a Bachelor of Fine Arts in Creative Writing and has been exploring the world of video games for as long as he can remember. He enjoys everything from large-scale RPGs to small, bite-size indie gems and everything in between.

From The Chatty
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    January 23, 2019 1:00 PM

    Josh Hawkins posted a new article, How to unlock Act 4 in Slay the Spire

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      January 23, 2019 1:31 PM

      How do I beat Act 2 Boss :(

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        January 23, 2019 2:04 PM

        which one? there are several different bosses that can show up for each act.

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          January 23, 2019 2:11 PM

          I have made it to and lost to the 400 HP Knight and the 300 HP Knight that summons two trash mobs

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        January 23, 2019 2:14 PM

        Slay the Spire's key strategy, universally, is learn how to fine tune your deck as best as you to be efficient , working with the relics you get. Keep your deck thin by using the card removal service at the shop, and bypassing on rewards if none of them fit the theme you have going. By Act 2, at least on average, I found I usually have hit on a few good synergistic cards and relics that grossly inflate how much damage you can do, or help to lay out balanced attacks with blocking at the same (eg without sacrificing one for another).

        The Act 1 boss is forgiving to a badly tuned deck, but Act 2 does not give that same leniency.

    • reply
      January 23, 2019 3:53 PM

      Finish Act 3.

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