Death: My power! Use my power!
Dracula: Soul Steal!
A rare voluntary example from Castlevania: Portrait of Ruin
VenomMyotismon: More energy! I'm hungry!
DemiDevimon: No problem, boss. There's all those people just laying there waiting for you! Remember to start the day with a good breakfast.
VenomMyotismon: I'll begin with a little snack! [eats DemiDevimon]
DemiDevimon: No problem, boss. There's all those people just laying there waiting for you! Remember to start the day with a good breakfast.
VenomMyotismon: I'll begin with a little snack! [eats DemiDevimon]
The Deceiver: Hey! All the other C'Tan are weak and being killed off. We should eat them before they die so their power won't be wasted.
(Sometime later, after this approach fails miserably (much to the Deceiver and Cegorach's amusement)):
Cegorach: Killing all of your allies in the middle of a giant war was apparently a bad idea, who would've fucking thought!
—The God-Emperor of Mankind's version of the First War, If the Emperor Had a Text-to-Speech Device