Further levels will always require three keys to escape.
The General Sibling Combinator has locked more enemy creatures in these cells, so be careful when picking what to fight. Your memories from previous levels might help you with the decision.
Good job! You managed to retrieve all keys, gathering gold in the process. Please continue to the next level immediately.
Game over! You have lost all your health. Try to fight those creatures that leave keys in order to finish the level.