I wanted to make it as an answer to greens " Creatures with power less then names power can't block it. Like a mercifull druid who can't attack a when a brave young weak being is in the way!

Wouldn't you just activate this creature after you've already declared it as an attacker anyway? Besides the odd case where your opponent tosses a Shock at your druid as a sort of Holy Day, the area in the quotes doesn't really do anything.

One solution to the problem jmg points out would be to add a sorcery-speed restriction. But instead of that, how about:

> At the beginning of your upkeep, you may have ~ become a 4/4 Bear until end of turn. If you do, ~ can't attack this turn unless an opponent [etc].

cool, i see this as a really good sideboard card vs control decks which tend to have less creatures.