I noticed yesterday that during a certain event that takes place near some streams and a beach, that Astarion kept mysteriously taking Acid damage and went down.
I figured that it was maybe an enemy that I couldn't see, or an environmental effect that wasn't drawing in properly...
So I stopped what I was doing and analyzed the situation. We're all standing in a small stream, but he's the only one taking damage... now why would- Oh. Oh wow. GENIUS.
Of course, the 5e playbook states that running water is harmful to vampires, which means that he was going to continually take Acid damage until I moved him out of it.
So it looks like the tadpole was able to influence his ability to ignore the harmful effects of sunlight, but not quite so strong as to protect him from other elements that vampires find hazardous.
This felt like a bit of a clue as to what the limitations of the tadpole's effects are on people.
I was honestly shocked and so pleased that the rule was actually included, and I'm glad that Larian is genuinely trying their best to adhere to the rulebook while still keeping things fun.
So be sure to keep your vampire buddies safe and clear! (Puddles and standing water are perfectly fine though, so if Astarion starts to stink, just make him "bird bath" himself.)