Death's Door

Bah, screw that. I'm not giving up a move to stay alive. My next character will be cooler, anyway.

On a 7-9, Death makes a bargain with you, in return for your life.

Now we're talking.

Definitely make the next character cooler is the best plan rather than making this one suck.

7-9 Death offers you a choice: bring your character back to life OR die and give your next character an extra move.

(Edit - typo)

As usual, John's nailed it.

Design goals dictate.  If this is more Apocalypse World hack than old skool homage then a light/no death penalty is absolutely the way to go. Certainly more interesting to *me*.  Players playing Dungeon World as a Red Box or OD&D proxy along the lines of LotFP will want/expect a harsh penalty for going zero. Doubt most of your audience is there.

Even Nu School AW has a "cheat Death utterly by taking this debility thing" going on, but maybe that's a good choice for that design. "You wanna know why I walk like this little carver?" (Why I'm less Hard/Hot/Cool) "Pull up a gas can and get wisdom..."

I think the great part about making it just a bargain, open to GM creativity, is that it supports all those. The bargain could still be a move, or a stat penalty, or something non-mechanical (a soul, love, etc.).

Speaking of that, I don't know whether you've come up with a Monster move to cover the "energy drain" ability that several undead have, but I want to advocate that you not follow the D&D standard that energy drain causes you to lose experience and levels. Although that can be rationalized, it still makes a lot more sense for energy drain to do something like reduce your physical ability scores than to remove your experience and levels (and consequently, for Dungeon World, your moves).