Motherlode 2nd boss (Azerokk)… can banish one of the elementals and keep refreshing to keep them banished through the entire fight. One less elemental to deal with. Note they cannot be banished if they focus and chase a player… just choose a different elemental then. Unlike the totems, banish doesn’t break on taking damage, so no worries about your groups AOE.
Most useful is Underrot… last pack before first boss… Befouled Spirit is an add which does significant group-wide dmg. Surrounded by multiple adds. Banish the Spirit… kill the other adds… cast banish again to release the spirit and deal with it alone.
In Shrine I have used it on the big Elemental add but somehow doesn’t work in higher lvl keys. First two definitely work and are very useful in 10+ keys.