Apart from the risk of losing a lab or temple very early, misfortune-2 should be survivable.

Devils are only troops, not commanders. If you want summonable SCs early, research to Blood-5 for Ice Devils. They're excellent combatants as is, and turn into full-on SCs with just a hellsword (though tricking them out with more toys never hurts). Your Cold scale very much suits them too.

While Devils and Fiends make great troops (not so sure about Frost Fiends though - they're mediocre missile troops IIRC), at one per summoning they're very expensive in terms of mage time until you can summon them in numbers later in the game (or make Soul Contracts).

You might want D3 instead of A3 on your Pretender. Van has plenty of air mages that you can recruit, while D3B3 gives you acces (with the odd item) to great spells like Curse of Blood (lvl 7 - summons a Vampire Lord) and Blood Rite (lvl 7 - summons a 10 or so vampires).

I don't think your Bless plan works. I'm pretty sure that Bless benefits depend on the original magic paths of the Pretender. That I would say is the main downside of your design; Van has some lovely Sacred troops that just cry out for a strong Blessing. Still, you can't have everything.

Mark