Touch of Fatigue before all others.
I picked heroism and false life with my first spell blending.. I took it again at 16th level and chose greater heroism.. Please dont select a cantrip... Arcane mark does just fine for getting u the extra attack..
I consider these:
lvl 1 Touch of the sea (playing skulls and shacles), crafters fortune, liberating command,
lvl 2 resist energy, see inv. protective penumbra (if dip into cross blooded sorc and orc bloodline)
lvl 3 Herosim, Resinoius skin
lvl 4 Fleshworm Infestation, calcific touch (with maxi,mixing touch thats 4 dex no save once pr round, put wording is weird, check with GM how it works with spellcomabt in your game), Mnemonic Enhancer (with greater spell recall you can get a 4 lvl spell back with 2 arcane points this ´gives you 3 extra 1 lvl spells - so you get more options)
But Heroism is the real gold here. Depending on wheter you already have a moral bonus... The See inv (unless someone is casting inv purge) and resist energy - in some fights this will make things real easy...