Can you just keep reversing/rewinding it into your deck and playing it again so that your ponies will keep growing?have 22 out and keep rewinding the last one so that you gain 22 damage per turn.
And the way you phrase it, every colt in elements gets +1/+1 whenever someone summons one. So you could log on and randomly get +1/+1
That is AWESOME!! I summon my Colt!! And now every second someone out there is also playing one therefore it grows by the second, I'll just wait for my minute turn to end and have a 60+ attack Colt!! ^^ Mwahahahahahahahahaaaa xD
Also, I like your idea to to make it 0/5 and 0/3 initially and make it +1/+0 for its new ability! =D But I'd follow SilentShadow's suggestion and make the micro have 0/4, cause then it'd be safer with fire's ultimate (and only xD) AoE. Maybe make the unupped cost 6
and have 0/6, just so the upped version becomes cheaper in the stats/cost ratio.
.... btw .... What's a Colt? o_O