A great team comp would be osa enu cra panda.
Enu mp reduction everything and gives buffs to cra, Cra takes range and does THE DAMAGE, panda vulns, does placements and a bit of damage, osa can buff, damage,map manip, summon for distractions when enus mp red isnt enough, and monsters have no mp compliments agi osa very well because of the tofu hit-and-run tactic.
If you wanna play eca so badly you can probably replace osa with it for this team. Idk much about the new ecas though ^_^
You dont need a whole character dedicated to be a healer with this team comp because nothing gets to hit you with all the -mp,-range and map manip. What little heals osa/eca , enu and panda provide is enough to sustain most dungeons.