So the Dream Visitor situation is pretty interesting, and you'll want to be careful with how you handle those warnings. I've seen quite a few players get themselves into trouble by ignoring the signs. If you decide to jump into the Astral Plane through that Planecaster thing to go after the Dream Visitor, it's not like a total disaster, but they definitely won't be happy about it. Though honestly, Vlaakith ends up being the real problem there anyway.

The trickiest part is probably managing those tadpole powers, since going overboard with them can lock you into becoming a mind flayer which isn't great if you're hoping for a different ending (Supreme Tadpole). Your companions have some pretty strong opinions too - Lae'zel especially gets pretty worked up about using them, while Gale and Astarion are actually kind of into it.

One thing that catches a lot of players off guard, and I learned this the hard way, is trying to go back to earlier areas after you've moved on to Act 2. That's basically a game over right there, which is super frustrating if you've put in tons of hours. The Dream Visitor might be playing their own game, but when they warn you about stuff like Vlaakith or where not to go, they're usually right about that at least. You can still be rebellious and make it work, but maybe don't ignore everything they say completely.