Whenever a creature an opponent controls dies, Altac Bloodseeker gets +2/+0 and gains first strike and haste until end of turn. (It deals combat damage before creatures without first strike, and it can attack andas soon as it comes under your control.)
7/18/2014 If a combat phase has two combat damage steps (because there’s an attacker or blocker with first strike or double strike), Altac Bloodseeker may gain first strike during the first one. If this happens, it will assign combat damage in the second combat damage step along with other creatures that haven’t assigned combat damage during that combat.
7/18/2014 If the ability triggers multiple times in a single turn, the power bonuses are cumulative, but the additional instances of first strike and haste are redundant.