Energy Drain
A successful energy drain attack inflicts one or more negative levels (as described in the ability). If an attack that includes an energy drain scores a critical hit, it inflicts twice the listed number of negative levels. Unless otherwise specified in the draining creature’s description, it gains 5 temporary Hit Points for each negative level it inflicts on an opponent. These temporary Hit Points last for a maximum of 1 hour. Negative levels from energy drain remain until 24 hours have passed or until they are removed with magic or technology. If a negative level isn’t removed before 24 hours have passed, the affected target must attempt a Fortitude saving throw (the exact DC is given in the creature’s stat block). On a success, the negative level goes away. On a failure, the negative level becomes permanent. A separate saving throw is required for each negative level. See page 252 of the Starfinder Core Rulebook for more about negative levels.
Format: Melee slam +24 (6d12+22 B plus energy drain); Offensive Abilities energy drain (2 levels, DC 22).
Source
Alien Archive pg. 154