Make Epic Spell: Mummy dust, Epic Spell: Planar Conduit and Epic spell: Dragon Knight to be on a cool down akin or longer than that of Epic Eldritch Summon.
Reasoning is: Crashes happen, Server transitions happens and while the summons are brought back, they do not have the wards they previously had and on top of that, they don't benefit from ESF stat buffs they did before transitioning. Furthermore, it would make doing dungeons split across servers less of a chore, or dungeons in general since it appears that at least one mob type per high level dungeon can now banish/dismiss summons.
For PvP: Unlike the Epic Eldritch Summon, Mummy dust, Planar Conduit and EDK are irrelevant in a fight, a simple scroll disposes of them. Them being on a cooldown of 10 minutes or not (after being dismissed) doesn't in any way, shape or form affect the balance of PvP.