Enraged Dragonhorse

Emerge {4}{r} (You may cast this spell by sacrificing
a creature and paying the emerge cost reduced by that creature's mana value.)
Torrent — {1}{r}: Enraged Dragonhorse gains
double strike until end of turn. (When you
activate this creature's torrent ability, put it on the
bottom of its owner's library at the beginning of the
next end step. Activate only once each turn.)