I meant you wait after casting Tressorhorn. Then after they draw, sac
mindslicer. Meaning wait until Tressorhorn is on the field, after they decide whether or not to try to counter him. When he is on the field, you lose 2 life, sac 2 creatures (Tressorhorn himself if you have no others or only one) and they draw 2 cards. Then you activate
mindslicer. Personally, I like
Thraximundar or
Nekusar, the Mindrazer or
Sedris, the Traitor King. Too high a price for the commander for my
blood, since Thrax easily overpowers Tressorhorn after 3 sacrifices from any player(s). If they goal is card draw, Nekusar both makes them draw every turn and stabs them for every card they draw.