@0neDragon Depends on how mana is used when casting. if the energy is harnessed outside himself, like Dragon Ball spirit laser stuff is, then it's infinite because the spell is formed outside him and thus his never-changing mana pool can supply as much as he needs. However, if the spell is internally processed like Ed's mental alchemy circles from Fullmetal Alchemist, then he's going to have to do some fancy layered casting to juice up the power since each part of the spell can only be a max of ten mana cost.
The main problem is that both Tina's fire lance and his fire lance both used 2 mp, just his magic attack value is ten while hers is... a lot. Because he is infinitely mana blessed, he might be able to do something like enchantments where it's TECHNICALLY not his magic attack stat that the mana is being run through.
Anyone else notice that the maid has a normal human ear in the second panel of the chapter, but demon/elf ears everywhere else?