Summon Duration?

Side-note: To this day I still haven't figured out which color is superior against a single target.

The only times green is efficient is if the target is super big and doesn't move much or at all. When its not, its so luck based whether they stay within your field or at the right spots. The corners are horrible for this, and you can't expect a moving target to happily stand still for you in the middle of the field. IIRC JoeTang said the difference of using and not using it is barely noticeable anyways, but I'd just use purple whenever the CD is off rather than switch at all. However, you don't have that luxury at gollux haha. On a related note, for comparisons with using them on gollux mobs, green field is actually lacking in damage and misses the mobs every once in a while, even when they run into the field, since the ball actually has to touch them.