Hmmmm... My summoner usually goes something like this:
Bio II,
Miasma,
Lightning
Bio I (has the shortest duration ~equal to lightning, so i cast it last.)
Plop down a Blue DOT AE (forgot what its called atm)
maybe a Miasma II if I'm feeling frisky.
and then i just rotate through Ruin, Ruin II, Fester (got an 800-something crit one time =P), and any other fun spells i feel like using like pet abilities, raging strikes, Virus on a boss, ect. Rinse repeat.
Its not hard...
AND DON'T FORGET EYE FOR AN EYE . I use it all the time in groups, toss it on the tank in big pulls or on a boss. Its the BOMB