Fun fact: This card doesn't actually work under the current rules. Changing the names of counters (assuming any card did such a thing) would have its effect in "layer 9" alongside things like Darksteel Plate, and the counters would need to be aware of their role by layer 7 to do what they're supposed to do (probably even earlier, lest cards like Rimefeather Owl yield strange consequences where they basically get to double-dip).

Also assuming the rules had the necessary fix, cards like Devoted Druid get pretty darn good with this.

Ooooh, wither go BYE BYE.

Other than hosing wither, I'm not sure why this is so expensive though. Most of your counters already are +1/+1, and the ones that aren't probably wanted to be. Edit: Ah, yeah, forgot the cards that do good things when you give them -1s.

For the rules problem, I guess you could make it "Replace all counters on your creatures with +1/+1 counters, when this leaves play put them back" messiness.

When this leaves play put them back is too messy. Don't put them back... there isn't a good enough reason for it.

I love the idea of using this as a backup plan for Darksteel Reactor. Hmm... It's still going to be 5 more turns before I'll win with this guy. Guess I'll just animate him and attack with my 15/15 indestructible dude.

Can this effect not live in layer 4 with the rest of the type-changing effects? Rimefeather Owl's ability would be dependent on it. I guess it would require a section in the comprules defining the "type" of a counter (which would depend on the ability that created the counter).

I also guess it would hose Flourishing Defenses, as the game would see Creature without counter => Creature with +1/+1 counter and not trigger (though I'm not certain on that)

Out of interest, would this instakill animated planeswalkers?

It sure would (unless the effect also made it stop being a planeswalker at the same time).

Gideon finds disgust in stooping to those methods, despite their ability to make him 12/12, and won't be loyal to you anymore.