"We must obscure the entrance! Perhaps the humans will believe their ally to be insane." even as Ubel suggested it the idea was shaky. If the group he brought had a competent enough caster they would see right through it. But it was better to make bad suggestions than say nothing... Though the ones hunting down Henry weren't coming up with anything.
"Or... maybe we uh... maybe we can have the scavengers burn down some nearby town? Draw the adventurers towards that? Surely Parsel can find a nice, little defenseless one? Maybe full of human children or elderly? That might draw them away..." this was even less plausible than his first suggestion... it may just draw more humans... but again Ubel believed talking to much was far better than talking to little. "Or... uh... maybe we can..."