Can use his action on a vampire with no blood.
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Gregory Winter
Unique ghoul with 4 life. 1 strength, 1 bleed.
Gregory can steal 1 blood (becoming life) from a vampire controlled by another Methuselah as a +1 stealth Ⓓ action. He can burn a vampire in torpor to gain 2 life as a Ⓓ action. During your unlock phase, Gregory burns 1 life.
Rulings
The two actions provided are not cross-restrictive. Each can be performed once during the same turn by the same minion.
Ghouls are monsters, not mortal.