Back to the original topic, I'd like to share a new pet I have: the Gnome Tinker. I play her with Mystera, usually with a prepared Mage Plate & extra Mana boosters prepared. What I really like about this setup, is that you get a steady increase of max Mana throughout the game, just by doing the stuff you are normally doing anyway; you get up to 5 max mana increase from exploration via the boosters; another up to 5 max mana increase from leveling (as granted by Mage Plate); and another up to 5 mana increase from picking up Mystera's boons, which is fueled by spellcasting, again something you plan to do anyway.
Very soon the build reaches 20 Mana, and going all the way to 23-25 is fairly guaranteed. Where being a Tinker comes into the picture is that you can pick up caster items from the shops, if you find at least 1-2 items you're already close to where a high-level sorcerer will end up, however you have more shop junk (more potions), and you have the possibility to branch into something more versatile should the need come up by picking up other items. It's less stable than the Gnome Sorcerer but more versatile. Gnome of course offers a steady supply of Mana Potions, which basically guarantees boss spikes, and even spares a few for spiking a few high-level kills along the way, or just as a way to counter an unfortunate Mana Burn.