I first used Metamorph on Mena. I then used Grimlic's Mirror on Mena. I then had two Menas. I don't think this is really a bug, but I feel like it's not very good for the game.
Well, while we are at mentioning commonly known Metamorphosis exploits, Metamorphosis resets the champion's base HP when it reverts. This has an almost unnoticeable effect in 99.9% of games but it does effect games where Aspect of Growth is in play. If you use Grow a few times and then use Metmorphosis, the current HP becomes the amount the champion grows. For example, Aspect of Growth has a base HP of 21. If you use Grow once, it's HP become 42. If you use Grow a second time, it's HP become 63. Now, if Metamorphosis is used on him and you Cleanse him, his "base" HP becomes 63, instead of 21, and so each subsequent use of Grow gives +63 HP. Edit: I should mention that he has Pariah so it can only really be particularly nasty if your opponent uses Metamorphosis.
This technically doesn't violate the description of the hero ability. Hero states that they explode when deployed in split bgs and that "only one copy of this rune may be played in a battle group". This is pretty different from the wording of mythical that states "When another copy of this unit is in play that you own, both it and this copy are destroyed." It seems like the intent is to give Heroes unique and mythical, but that isn't how the ability is currently worded.
