Phantasmal Mount
{1}{U}
Creature -- Illusion Horse
1/1
Flying
{T}: Target creature you control with toughness 2 or less gets +1/+1 and gains flying until end of turn. When ~this~ leaves the battlefield this turn, sacrifice that creature. When the creature leaves the battlefield this turn, sacrifice ~this~.
Shifty Doppelganger
{2}{U}
Creature -- Shapeshifter
1/1
{3}{U}, Exile ~this~: You may put a creature card from your hand onto the battlefield. If you do, that creature gains haste until end of turn. At the beginning of the next end step, sacrifice that creature. If you do, return ~this~ to the battlefield.