How about a Thorns skill? What I mean, is, her legendary could reflect a portion of damage recieved. Could be proportional, like, i dunno, 40% or something.
Thorns that sprout from the ground and bind 3 heroes, unable to move or attack for 5 secs.
Or deal like.....5k true samage to entire enemy party at unlock, then incremental dam per skill increase. Something to get the whole squad hurt