FlockeSchnee: (That ... is problematic. Even if Tanea would be cool with it, which she wouldn't. The "cooldown" for summoning is 3 turns since the summon disappeared. The Ice Elemental and Holy Guardian will vanish now. And Gilius just sent his Stone Elemental to explode into pieces. Your next best bet would be Yeenwi summoning another undead for Turn 12 -the ghasts died on turn 8-.)
(I think everyone gets more spell casts because it is Turn 10.)
This is what Doc said on the new update: ATTENTION ALL SPELL CASTERS, as it is turn 10 you get recharge of your spells, meaning that if you had 8 spell casts at the beginning of the game you get another 8 spell casts now plus whatever you had left from before turn 10.
( So I think that means everyone can cast like they just started the game from the beginning plus whatever spell casts they had leftover. )
(edit: found what you were talking about the 3 turn limit. Here is what I found on spell summon info from Doc.)
Spells that summon creatures - the creature will stay with you for 5 turns or until slain/ banished.
Magic items that summon creatures are a little different. The creature will stay with you until slain/ banished. Then it is 3 turns until you can summon it again.