The Waterfall Giant is the boss you face during Act 1 in the Underdocks Biome in Slay the Spire 2. The boss seems easy at first but in my experience it is deceptively hard and taking down the boss does not immediately end the boss fight.
Instead, the Waterfall Giant builds up a charge throughout the fight and unleashes a final detonation after you reduce its HP to zero.
Because of this mechanic, many runs end with players killing the boss but still dying to the explosion afterward. This guide explains exactly how the fight works and how to consistently beat the Waterfall Giant.
The entire Waterfall Giant boss fight is about a charge mechanic that scales over time. During the fight, the Waterfall Giant boss builds charge stacks each turn and these stacks power up a final explosion attack. When the boss drops down to 0 HP, it still performs one final move.
This move is a detonation that does a ton of damage based on accumulated charge. This will create a damage race, the longer you fight the Waterfall Giant the bigger the final explosion will be. You must survive the final detonation to complete the Waterfall Giant boss fight.
Things to Avoid
There are three main reasons why this boss kills so many runs.
Slow Decks
Decks that rely on long scaling strategies often take too long to finish the fight. More turns means more charge stacks and a stronger explosion.
Entering the Fight with Low Health
Even if you beat the boss the final detonation can kill your character if your HP is too low. You need to come into the boss fight with max HP, and then take as little damage as possible while trying to end the fight fast.
Forgetting the Final Attack
Most players deliver the final blow and forget about the detonation with no block prepared. They end up dying from the detonation immediately. The Waterfall Giant punishes slow play and poor planning more than most Act 1 bosses.
Do Not Stall the Fight
Another big mistake you need to avoid is stalling this Slay the Spire 2 boss fight.
Avoid strategies like:
- Spending several turns stacking scaling powers
- Waiting to assemble long combos
- Playing overly defensive early turns
The Waterfall Giant is effectively a turn timer boss. The longer you stall, the more dangerous the final explosion becomes.
How to Defeat Waterfall Giant
The most reliable strategy is to end the fight quickly. Your goal should be to reduce the number of turns the boss has to build the charge attack.
Strong options include:
- Cheap attack cards
- Multi-hit damage
- Temporary burst damage
- Potions that boost damage
In Act 1, your early decks that lean a lot into damage often perform much better against the Waterfall Giant. So having an offensive setup is better than having defensive setups.
If your deck spends several turns setting up powers or scaling effects, the explosion will likely become lethal. Even if you plan to kill the boss quickly, you must save defensive tools for the final turn.
The best approach is to prepare for the killing blow. Keep at least one block card in hand and make sure to save defensive potions. Having relics and abilities that provide extra defense help. I recommend trying to finish the Waterfall Giant on a turn where you still have energy left to generate block.
A lot of players make the mistake of dealing damage inefficiently across many turns. Instead, try to compress damage into fewer turns. For example, you should use card draw to create large attack turn, save damage potions for a burst turn, and finally I’d say it is best to stack vulnerability or damage buffs before attacking.
The goal is to shorten the fight length, not just deal steady damage.
The final explosion is unavoidable so your HP going into the Waterfall Giant boss fight matters. Before you enter the boss fight, avoid taking unnecessary damage from the hallway fights, rest at the campfires if you are low. Lastly, save up on defensive potions as much as possible.
