Love this concept. I might be tempted to make it uncommon and make the summoning requirements a bit looser or easier to achieve.
As it is now, I feel like:
- This card would be a bit on the weak side. Summoning Flame lord would be incredibly difficult.
- It would mostly be used as a Succubus factory, which would make it not so interesting. Have 2 imps? Play Maleficar and get Succubus. Have 1 imp? Play 2 Maleficars and get Succubus.