The P/T/CMC may be anything, but it makes sense to have an "enters tapped" creature somewhere in red this set.

Ha! Yes, indeed it does.

Was going to put this in at uncommon, but there's other creatures we want more for the moment. Could also add another ability so it's less of a "less good elite vanguard or diregraf ghoul" and put it in rare.

I think I like this as a bigger creature. Coming into play tapped doesn't mean anything on turn 1 in this set. A large 6/6 creature that doesn't stop your all 'All tapped' shenanigans on turn 5, however, means more.

Hm, quite possibly. In fact, it should probably have some positive static ability too, so there's a reason being able to play it before attacking is good. In fact, maybe the drawback could be tacked onto another creature we already have that's a little strong.