The way loot is now, it's easy to build a high resists suit with LMC, LRC, SDI and mana regen.
So, one fun farming template would be
Magery
Mysticism
Spellweaving
Eval
Inscription
Focus (not only mana regen, but acts like Eval for Mysticism)
Med Or Resist*
*As you scroll up the other skills, take the points from this last skill.
Some things, especially skills you aren't using the mastery for, can be on jewelry or other items (several +15 magery event spellbooks are out there, as you won't be able to immediately afford the 25-30 SDI slayers or 40-50% SDI non-slayer books from September 2017's event - there are also crafted spellbooks that can have +10 or better in 1-3 casting skills, plus any additional bonuses if a Scrapper's Compendium). One goal would be a 2016 Halloween's Katakotl's Ring, or its weak sister the Crystalline Ring from Prism of Light.
My caster with this template is 100 Inscription, 120x5, and 60 points in Med, from using a +10 Focus talisman, and having +20 Mysticism and +10 Med (and a wasted +10 Resist) on a Katakotl's ring (the ring, allows the casting skill to be chosen, but is fixed after the choice). You can do something similar with a Crystalline Ring (but the skills are Magery and Focus). My total suit, mostly cheap artifacts, loot that anyone can get, and a couple of reforged or imbued items, is overcapped on INT Bonus, LRC & LMC, all 70s resists even if I cast Protection, +16 Mana Increase, FC 2/FCR 4, 68-98% SDI (depending on book equipped), 27 or 28 Mana Regen, and about 10 HP Regen. Half the suit still pre-dates Stygian Abyss, so are fairly low items in comparison to current loot. Oh, and this suit has ZERO resists in the neck slot, from using a pendant of the magi.
Once you find out about masteries, the Skill Mastery you want for the template is Spellweaving.