Turn against, creatures lose haste.

Leaveascar

Bug effect: The creatures stolen with Turn against lose their haste and become disabled or have summoning sickness as if they were just cast from your hand.

Bug trigger: Creatures on the board on both sides. The creatures don't seem to matter. Harness the Storm on the board, I use turn against to steal creature(s). They show they have haste and are ready to attack. I cast a few more spells. After two or three spells, the haste symbol disappears and the creature will not attack as if I just cast it.