Elemental Combos
^ That wiki page is likely to be your best resource; the wiki is great!
Otherwise, skills which can be used in combos say so in their descriptions – if you hold your cursor over them as well as range etc. they will say they are combo fields or finishers. You need one of each for a combo, so if someone lays down a field (a guardian circle, a line of fire, a smokescreen…) and someone else uses a finisher through or within it, you get a combo. Finishers can be projectiles (firing through the field often adds a condition to your shot), blasts (healing spring + a blast of some kind spreads healing to everyone in the area) or a number of other things.
Check over your skills and see if they mention use in combos. You can combo off your own fields if you want to experiment, or watch out for others to experiment!
Thanks,
Somehow I had though there would more to it.
Non-the-less it does make the water spells much more useful when used with people who understand how to partake.
Can a single finisher activate multiple overlapping fields? In other words, if I drop a fire field and a water field, and then send a blast through it, will it both buff and heal the people on the other side?