exp 200% event & 200% exp event , and happy-hour , stacks whit blessed iris or psp ? or pbi and pssp ?

XP cap is at 250%

Therefore you can use all pots u have, but you will be capped at 250%.

The only exception is phi/pssp, which give 300% themselves, thus giving you 50% more than you would normally get.

During events, you can use small exp boost pots to get 50% additional xp and using the max possible.