Its a bit OP cuz once u use Mirage on a opponent's creature u get to destroy it and u get that creature on ur field. and then mirage is on top of ur deck which u can draw it everytime if u use it every turn
I think you misunderstand, so example time
P1
P2
ok, so P1 wins the toss, and plays some cards,
P2 does the same,
5 turns
P2 plays a Lava Golem and beefs it up.
3 or 4 turns ...
P1 uses Mirage on beefy Lava Golem.
P1 has a Lava Golem with the passive ability Mirage and P2 still has his original. Play goes on for a few more turns.
P2 then targets the Mirage with a firebolt and it is destroyed and a copy of the spell Mirage goes onto your deck.
If you kill the original, it doesnt do anything to the Mirage and vice versa. If possible, Mirage (ability) is not visible to opponents, so they wont know what to target and spend weak spells on.
You understand better? It is weaker than the spell Twin Universe, that does pretty much the same thing. You cant copy a creatire and give it adrenaline, or use this for Pegasi Blitz or anything. It makes a 'illusionary copy' that is detroyed 'at the slightest touch'.
dig?