In the settings there is a spot where you can check to auto cast good spells on your self if you have bad guy targeted. So if all 5 of my guys are wailing on a bad guy I can press my heal button and they will all cast lifebloom or rejuvenation on them selves (minus the tank). Now, lets say only one druid needs healing. I can target the druid with my tank. Press my /assist tank button and that will make all 5 toons target the druid in question. I press the same button for the lifebloom/rejuv and all 4 druids will cast on the one targeted giving them a very cheap, instant cast, heal to full life in a tick or two.

This target then assist heal also works well when I drop a druid and have a guild member join my group. If they need healed, just target with my paladin. /assist and heal.