Arcane Tricker sounds more useful. Having an extra bonus action doesn't seem that useful for someone at range. Make sure you select Mage Hand. I thought it was an automatic spell, and now Astarion doesn't have it. Extra bonus action is extremely useful as you can use dash and hide at the same turn. This way I solo'd many encounters which would be deadly with a group. So Thief all the way.
Solo kill list: One stupid evil (displayed alignment) Githyanki warrior, a dark grove, a Zhentarim hideout full of "experienced" rogues, half a Goblin camp including two hobgoblins, two minotaurs, a bunch of underworld monsters and their wannabe sorcerous overlord
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