Dead Cells

This requires you to bring 10 skill blueprints to the Collector. You do not need to spend cells on unlocking the skills, bringing the blueprints is all that is necessary. Blueprints are random drops from killing enemies.

You can check your progress towards this achievement in the Skills section of the Progress screen that you can see by talking to the character next to the Daily Challenge door at the start of the game. The achievement will unlock when you bring the 10th skill blueprint to the Collector.