To tame a Deinotherium, approach slowly with a Beer Jar in your last hotbar slot. Watch for three acceptance signals: head shaking, ear flapping, and trunk shaking. Once all three appear, position yourself under its trunk to let it grab the beer. After it drinks, retreat for 30 seconds and repeat. If the trunk rolls up or ears press flat, reset your approach — the creature will become hostile if you push past rejection signals.