[@1Charak2] There is no limit (in terms of set) for types of magic, since the cards are balancing methods rather than the spells themselves, to ensure that no crazy pyromancer casts Explosive Impact (5 damage to target creature or player) on turn one, for example. I wasn't around for Phyrexia, was that the one where you could lose life to pay mana costs? If that's correct, you could roleplay it as a kind of blood magic - slicing yourself across the palm or whatever. This could cause people to be more than a little creeped out by you, especially in public, so it wpuld probably be good for roleplaying. As for particularly powerful spells, PM if you are not sure about the fairness of the card, before you post. It will probably be okay, but if, for example, you have an NPC important to the roleplay on your side and your opponent casts Hero's Downfall (Destroy target creature or planeswalker) I will almost certainly intervene. In general, avoid using "Destroy", "Remove from game" or "Exile" spells on story-important targets, unless they're temporary.