Terror of the Eight-Legged

When Terror of the Eight-Legged enters the battlefield, torment each player. (To torment a player, that player loses 3 life unless they sacrifice a permanent or discard a card.)

Spider creatures you control cannot be blocked.

Whenever a Spider you control enters or attacks, each player discards three cards or mills three cards. For each creature card discarded or milled this way, Spiders you control get +1/+1 until end of turn.