How to Transform, Use Titan Attacks, and Grant Powers
Shifting, Attacking, and Exiting
Once you have acquired a titan shifting power, you can transform on demand during exploration or combat. Press B to shift into your giant titan body. While transformed, you have access to three special titan attacks bound to X, C, and V alongside your regular movement. When your fight is finished and you want to return to human form, press B a second time to peek out of the titan's nape. While peeking out of the nape, hold your crouch key to safely get out of the titan body.
Setting Titan Powers with Commands
If you are playing in a world with cheats enabled and want to grant yourself shifting abilities immediately without hunting for spinal fluid or special villagers, open chat and run one of the built-in shifter commands:
/daot shifter set @p attackgives you the Attack Titan power./daot shifter set @p armoredgives you the Armored Titan power./daot shifter set @p colossalgives you the Colossal Titan power.
Once the command runs, press B at any time to test your transformation and special attacks.