I continue traying to lear how to use the mage, so I do not consider an expert on it, despite I think that is the mage with more versatility...
However since my own experiencie is that you need to focus your spell book a little bit... I see on it several strategies (Mana drain, Creature summoning and Attack mage... ) two possible strategies could be ok, but three is maybe too much...
In this way from my point of view I will reduce the Mana drain strategy since it is expensive (12 mana just to summoning the Mana Siphon...)
So I will sugesst to put off:
1 x Mana Siphon
1 x Suppression Cloak
and also maybe:
1 x Mordok's Obelisk
1 x Suppression Orb
Regarding the attacks, why 1 x Hurl Boulder?(spellbook of 4), I find better for your mage 2x Lightning Bolt instead, If you join it with your Lightning Ring you will have also a strong attack.
I find Thunderbolt really expesive fo one attack, you have better options as Lightning Bolt, that you already have have, or Arc Lightning (cheaper to spell) but usefull at least.
Regardign creatures I will change Whirling Spirit (it could not summoned by the Gate of Voltary) and Darkfenne Hydra sounds good but to me never works as I espected... I will add another Gargoyle Sentry to defend you or yout conjurations and another Gorgon Archer if you can, this creature is fantastic and let you to use distance attacks and weak condition... it is somenthing to fear...
For the Enchantments I do not have complains test it and lets see what you need, what it is not useful... for Equipment I di not find for you the Arcane Ring usefull... and definitely you need another Elemental Wand, probalyI will change your Purge Magic (12 mana to spell it!) for extra Seeking Dispel and I will take in consideration to include some Force Push and some Wall of Thorns to crash your opponent with...
All of them are suggestions, but as silverclawgrizzly said play it a couple games and develop it. ;-)