How would this pan out?
The scenario question is that you are player A and your opponents are B,C,D.
B: has a Knowledge Pool under their control.
C: has a Possibility Storm under their control.
D: has a Eye of the Storm under their control.
How does Rampant Growth resolve if at all?
You're just trying to keep people busy, don't you... ah well, here you go (assuming the player letters are in turn order, Rampant Growth from their hand, and probably a lot of other assumptions described as relevant):
Triggered abilities trigger at the same time and are put on the stack in APNAP order (active player, non-active player/s). This means that A casting Rampant Growth will trigger all of the other mentioned cards, and those triggers will resolve last-in, first out, meaning Eye of the Storm's trigger resolves first, Hive Mind last.
Eye of the Storm (and I'll assume no other cards being exiled with it) will exile the original spell, then have player A cast a copy of the spell. This will trigger Hive Mind an additional time, however none of the other cards, as the copy isn't a card and isn't cast from A's hand.
The topmost object of the stack is now Hive Mind's last trigger, creating three copies of Rampant Growth for B, C, and D respectively. Assuming nothing else happens, they get to search their libraries in opposite turn order as their individual copies resolve. None of the other cards are triggered, as Hive Mind creates copies which are put on the stack directly, not cast. Once all of that resolves, your copy (cast due to Eye of the Storm) resolves and lets you search for a land.
The next object on the stack is Possibility Storm's trigger. The original spell has been exiled, but the ability does what it can and proceeds resolving, making A exile cards until revealing a Sorcery. If A finds one, they get the option of casting it, and will have to put the rest of the exiled cards on the bottom of the library. If they do cast it, it will trigger all other cards again as described above, creating a loop until the player chooses not to cast a card, or fails to reveal a Sorcery. I will skip to that point, as you have all the necessary information above to figure out what happens inbetween.
Knowledge Pool's trigger is next to resolve, but it won't do a whole lot, as the original Rampant Growth has already been exiled. The rest of the ability depends on exiling the spell, so nothing in particular happens here.
The first Hive Mind trigger is now resolving, creating another round of Rampant Growths for player B, C, and D. Once they're done resolving, the stack is empty, as the original spell has been exiled before, making player A get one less land as everyone else from this whole shenanigans.
September 26, 2016 11:26 a.m.
You're right, as best as my lack of coffeed mind can tell, except for this bit:
_ If they do cast it, it will trigger all other cards again as described above, creating a loop until the player chooses not to cast a card, or fails to reveal a Sorcery. I will skip to that point, as you have all the necessary information above to figure out what happens inbetween._