Small but Brawny is a passive skill in the Wildling skill tree which reduces your shaman's size by 4% for each skill point allocated.
The maximum allocated skill points is 5, which, when fully upgraded, decreases your shaman's size by a total of 20% when fully upgraded.
This skill will affect both shamans in maps with multiple shamans. A smaller shaman will be able to squeeze through some holes that normal-sized mice cannot.
This skill works together with the Big Shaman skill.