Holleas is the Phoenix Elves’ champion with the highest ceiling of potential game impact and arguably their best champion to take over Maldaria’s role to carry the game if Maldaria needs to sit out.
Also, it is one of the main ways for Phoenix Elves to have a strong range game. Holleas + Ember mages can fight at range effectively against many factions.
However, Phoenix Elves need to shift the focus on playing around her to get maximum value as you probably need to use all your movements to reposition her every turn.
She is still good to support an active Maldaria, especially helping her during pushes to bring forward fresh units.