Is this card broken? I realize it insta-combos with Altar of Dementia, are there any others? Does that make it too strong?

I think it's a little too easy to combo with right now. Maybe "At the beginning of each end step, for each card put into an opponent's graveyard from anywhere this turn, put a 1/1 green Insect token onto the battlefield."

The 'not really a combo's seem pretty strong with this card, too. Mind Sculpt becomes seven 1/1 insects for . How many creatures do you need before you've defacto won the game? I don't know. Maybe I'm overthinking it?

I think it's a valid point, I was overthinking it trying to justify the op-ness. Back to the drawing board then :(

Maybe restrict it to creature cards.

I was thinking that, but I didn't wan it to be completely useless against creature-light decks. I might do a repeatable activated ability where I mill one, then put 1/1s equal to the milled card's CMC.

This is a 6-mana three-colour mythic. With no other abilities, even. I think making some bizarre janky cards like Mind Sculpt better is fine. Sure, it turns Traumatize into instant-win, but so do many things. I like that it makes all your kill spells and discard spells a bit better.

Also turns Boom // Bust into instant wins, too. I'm not saying whether that's fair or not, mind you. Fair, when it comes to Mythics, can be rather hard to guage.