I should do that one day (Mirrowing + Cultivators + 100 Zombie tokens from Lili + (x) Might of the Masses) just to hit the damage cap for my stats page.
There is no stats-page on Steam afaik. So I can't be bothered.
Regarding Mirrorwing vs Cultivators, it's the same. If you target a cultivator with 4 might of the masses and 100 creatures, it gets +400 power and when the ability resolves, all your attackers get those +400 power. If you target Dragon, it'll look funny with 400 spells on the stack, but the end result is the same.
With 100 zombie-tokens, you'll "just" do 400*100*cultivators double-damage count. If you make 100 cultivator tokens instead, you will hit for 400*2^100 damage. Get ready for it:
507.060.240.091.291.760.598.681.282.150.400 damage.
Using Short scale names, that's 507 nonillion, 60 octillion, 240 septillion, 91 sextillion, 291 quintillion, 760 quadrillion, 598 trillion, 681 billion, 282 million, 150 thousand, 400 damage.
So like overkill but not unlimited or anything crazy. Due to the clients restrictions, it'll be different though. You should go for 100 tokens, and of those, just 8 of them need to be cultivators if you go with Might of the Masses * 4. If you don't want to bother with casting 4 instants, just do 20odd cultivator tokens and 80 other tokens. That'll bring them to 9999/9999 regardless and you hit for a million ish.