A chupacabra that successfully hits an opponent can make an additional attack; on a hit, it can suck blood from that opponent automatically once per round, dealing an additional 1d4 points of damage. Upon successfully draining blood, the chupacabra is invigorated, gaining a significant boost in speed for 10 rounds similar to the haste spell. The invigorated chupacabra can still drain blood - and in so doing increase the length of its invigoration - but it gains no additional effects.