I never got the quest to get my lvl 75 minion I'm currently a lvl 90 and I have no clue where to get the minion besides failing the khrystalis boss 13 times and yes I've counted it lol
In order to get your minion, you needed to get your utility spell in Wintertusk.
In order to get that, you needed to get your other utility spell in Grizzleheim (Thief of Spells: level 35, Mirkholm Keep - gives you Supercharge). After you have Supercharge, the next spell comes from Wintertusk (The Runedown: level 55, Sudrilund - gives you Insane Bolt).
Here's a thread from Central that lays the Grizzleheim/Wintertusk instructions out in a way that's fairly easy to understand:
Once you've gotten your Insane Bolt spell, you should hopefully get a couple more notices: one from Halston Balestrom, who will send you out after your minion (Kapiti Plain: level 75 - gives you Mokompo), and another from Friar Nolan in Avalon, who will have two more utility spell quests lined up for you.
For your Avalon spells, one comes from Friar Nolan in Caliburn (No Pain, No Agravaine: level 72 - gives you Enfeeble) and one comes from Fianna Yellowknife on the High Road (Always After Me Charms: level 75 - gives you Healing Current).
Once you've done all this, you should be caught up on everything.