So they reaaaaally want big spell/buff paladin to work eh.
Possible problems: Traditionally Paladin has always been a minion heavy class, not spell heavy. Yes spell Hunter exists, but Spell Hunter had a ton of support for it, good pre-existing spell cards which were good tempo (Animal Companion) etc. I'd still be concerned about how many good spells you'd want/be able to cast with this. This+any buff seems pretty good, but can you get it to work consistently? How game-winning would it be? What's your gameplan? If you're choosing SMOrcing with big minions as the gameplan, how is this better than pre-existing decks (see: Even Paladin)? Can it make the cut and replace cards in a pre-existing deck? (Personally doubtful) Can you afford to waste 4 mana in such a deck for this payoff?
I'm going to lay off judgement on this card for a bit, because the payoff is pretty good, but I'm not sure whether it's good ENOUGH to make a deck work.