Disarming traps. Why a have advantage but not Thieves' tools bonus

Alejandro
Level 4
1 year ago (edited)

Clear sky, citizens

Please help me to comprehend one thing.

I have a Island halfling rogue in my party. And when she tries to disarm traps, instead of having +7 Thieves' Tools bonus (as I expected) she has only +3 and advantage. Why?

PS That was on Caer Lem location. 2 traps where there are wooden stairs in front of the door behind which 4 surviving soldiers are hiding