Alara Reborn — Mythic
Legendary Creature — Zombie Assassin
5/1/2009 : Thraximundar’s middle ability resolves during the declare attackers step. The defending player sacrifices a creature before it would get a chance to block.
5/1/2009 : Thraximundar’s last ability triggers whenever any player (including you) sacrifices a creature for any reason. It doesn’t trigger only when a creature is sacrificed due to its middle ability. Note that Thraximundar itself doesn’t allow you to sacrifice any creatures.