2 Defense are good - otherwise they are just too much high-value targets which are far too easy to kill.
High value - easy to catch - you do it first priority. He would die every game.
4 Body and 6 Mind points are good. The proposal to have one summon token per mind point, costing an action each, is also good.
Having one extra summon for the cost of a BP is also good - the combined cost is the action plus the BP, so this is quite expensive.
I don't think the summoning of skeletons is too strong. All six of them defending on black skulls are strong like two or three henchmen. Plus if they can't open doors, have no long range attack, no diagonal, no good armor - they really are limited. More so if you use the original HQ Board with one-square wide aisles; there they would stand in the way more than they'd help.
Now for me there can be a problem if you allow him to gain BP through dying models. Suddenly the cost of a BP is not as expensive as it was intended to be.
Maybe you give him a spell that costs an action to use - "Cost: Action. Discard this spell. Gain 1 BP if a model died in this room this or last round".
That way, you have a limit - the amount of these spells you put in the card deck.
You have additional cost of one action to use the spell;
and finally it is quite situational - you have to be at the right time in the right place to use it; so in some cases you have an additional cost of one movement in a direction you didn't want to go.
I like your way of building your hand of cards.
I would do it slightly different, of course, because it's me and i always have my own ideas....
If you allow him to draw MP cards each turn, he'll scan the entire deck in a few rounds. Why not allowing him to draw as many as he needs to fill his hand (maximum MP cards), plus two. Then put under your deck just enough cards to have MP cards on your hand.
(or the other way round - first put under the deck a maximum of two cards, then take new cards)
That way, you can make an additional artifact that allows to draw more cards, a second artifact that allows to hold more cards on the hand, a third artifact to allow to discard a third card. A spell scroll allows you to search for a distinct card. You also force him to use his spells, otherwise he wouldn't find the uber-card he searches in the deck.
Well, but that's just me.

I like the way how personal card decks work.