The Watcher in the Water (ES) pw21 creatures can't block unless their

creatures can't block unless their controller pays {1} for each of those creatures

choose a number between 1 and 5

Whenever Spring-Leaf Avenger deals combat damage to a player

Put target permanent card from your graveyard on top of your library

a legendary 1/1 red Hamster creature token with trample and haste

The Watcher in the Water (ES) pw21 creatures can't block unless theirThe Watcher in the Water enters the battlefield tapped with nine stun counters on it. (If a permanent with a stun counter would become untapped, remove one from it instead.) Whenever you draw a card during an opponent's turn, create a 1 1 blue Tentacle creature token. Whenever a Tentacle you control dies, untap up to one target Kraken and put a stun counter on up to one target nonland permanent.