Hello and welcome Yamikodomo.
There are three basic ways to increase casting points...
1) Research the wizard skills from Casting Specialist I up to Casting Specialist V. Each level of Casting Specialist will add 10 casting points.
2) Build the wizard's tower level 2 and then build the casting chamber for plus 10 casting points.
3) Build the wizard's tower level 3 and then build the item forge and finally forge an item with casting specialist for plus 10 casting points.
The total maximum when all of these three are finished is 90 casting points.
Note you may sometimes find an item with casting specialist while exploring a crypt, campsite, or ancient ruins.
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Here are the UPatch1.4 changes to the NATURE SHRINE...
EFFECT: 15 Gold, 30 Growth. Production bonus was removed, Gold comes from Mother Earth.
SPELL REWARDS...
+ City Quake, + Concealment, + Free Movement, + Stone Skin, - Static Shield, + Basilisk.
UNIT REWARDS...
Low reward: GoblinBeetle,2Wolfrider; Shaman,2Abomination; EE,2Boar; Manticore,Catmaster,Hunter; 3Penguins; 3Minotaurs; Hydra,Slither; Waterdancer,Lurker,EE; Treeman,Druid; 2Centaur.
Average reward: 2Trolls,1Darter; GoblinPioneer; Doomwolf; 2Herbalist,1Boars; 2EE,1Minotaur; 2Hydra,1Slither; 3Yeti; 2Treemen,1Nymph; ElvenPioneer; FairyDragon.
Strong rewards: 2Kharagh; 2Glutton; 2Basilisk; 4 EE; 2DoomWolves; 2Wyrm; 3Hydra3Slith; 2FairyDragon; 2Leperchauns; 4Hydras.
I hope this answer helps, good luck!
[This message has been edited by flyguy (edited 03-23-2014 @ 06:24 PM).]