I can see that the Tinkerer has skills that provides extra enchantments for items. Could there be a skill branch providing extra summoning (and summoning support). One of the summoning could be some a (powerfull) genie/warrior/golem aka guardian/bodyguard

The wizard should also be able to do the spell of making like the tyrant as an arcane expert. 

Could some of the skills provide extra powerfull overland spells e.g. worldwide spells affecting the world aka armageddon (small vulcanos erupt everywhere), a greater fertility and lesser shadowlands, strategic level earthquake - a smaller area or the whole world, dealing damage to every unit not stationed in cities or guarding or in boats.

A skill that provides a teleport.  

I would also like the wizard to have a scrying pool or maybe the (mid level) skill to cast arcane monolith.

Overall the wizard should be expert on wizardry things and arcane subjects. Summoning, spell casting, spell resistance, mana use/gathering, number of spells, the kinds and types of spells. Also make the clairvoyance (+1 casting) to a expensive spells requiring a lot of mana to expand your limits as a spell caster.