After getting lvl3 and giving it a second thought, I ended up picking:
1. Blade Ward and Dancing Light for my cantrips.
- Any of the offensive cantrips are worse than making a ranged normal/sneak attack with 17-18 DEX and kinda oblige me to use the warped headband of intellect.
- I don't find Blade Ward strong, but given the fact that you can Blade Ward, sprint (I decided to go for a chain of liberation + haste helm combo later) and make an off-hand crossbow shot in one turn resulted in a green light here.
- Dancing Lights can be considered not that useful because Astarion has darkvision (12), but sometimes I did find myself up high with a disadvantage on the enemy below, because it was obscured (spider cave...). In this scenario you can't make a sneak shot anyway, because of a disadvantage, so you can cast the lights and make an ohh-hand crossbow shot.
2. For the trickster spells I got Disguise Self (thanks to JandK for a cool suggestion), Sleep and Color Spray. No comments here I think.
3. For a free spell choice I ended up picking magick missile over the familiar. Familiar seemed like a good pick, but considering the existence of the sapphire spark (again thanks to JandK for reminding me that) I thought it a stronger choice. Sometimes you just need to split damage and an enhanced magick missile is a perfect pick for that.
I think I am good to go now!!
