Yes, but you need the same number to match 2,3 or 4 enemy dragons. And you need only one to match smaller creeps, and 2 to match medium creeps.
And your opponent's creeps are vulnerable to cc, whereas yours aren't. Combined with CC, this makes for some mean options.
Would love to use these with a time combo, i.e. reverse time. =)
I like the idea, but I think you should choose between making them untargetable or making them quite good attackers. Both is a bit too much.
For your interest I compiled a quick list of strategies which will be devastating against a deck that relies on Mirrors (of which you should stack 6 in a deck to be reliable - gotta get them out before your opponent gets his critters out!):
- Blessing on an early creature, maybe a Pegasus. Toss on Miracles for good measure.
- Devourer denial and lifedrains early. Heck, Steal is deadly all by itself.
- Thorns with heal spells/empathy, even frogdrenaline or spirits.
- Aflatoxin on your own thing, then skull shield and hope he isn't rolling a troublesome dual deck. Sexington's would rock here!
- Explode the Mirrors, then anything goes. Phoenixes for good measure, or even a single Fire Spirit.
- Permafrost combined with anything, probably dragons. Poison decks work great too.
- Gas decks, FFQ, any form of flying weapons won't trigger Mirrors.
- EQ denial doesn't work completely, but any deck involving Diamond Shield (especially with PA) shuts this down completely.
- Firemasters or flying Titans are about all you get. This element will probably have the roughest time, especially mono.
- Butterfly Effect decks are common enough, and Dissipation Shield takes 2 quanta per Elite Phantom to run.
- Recommend deckout, time decks are built for that and there's not much else here unless you count Pharaoh - which I don't because hardly anyone uses him these days.
- Mirror vs mirror, or possibly Mindgate could prove useful.
There you go. Blessing decks, darkness/earth denial, healthrough, shields, creature buffs, perm control, growth creatures, poison, flying weapons, creatureless, deckout... that's a lot of common strats that shut mirrors down HARD. As I said before, your opponent is willingly triggering the effect on his turn - heh, I all but convinced myself this card is underpowered!
It's a viable card, though - just situational.