Exo Guide Tentative
Why play Exorcist?
Exorcist is a competitive, fast scaling, micro intensive tier one class that heavily out performs other classes in the e180-e300 myst range. You can start running Exorcist as soon as you can unlock his final skill; 
Battle Trance, wherein he's immediately an extremely powerful class to play. Being a very fast profiting class Exorcist is popular for rapid progression through this stage of the game.
Exorcist runs follow a very simple progression at their core consisting of stacking excess hallowed clicks followed by cycle through your burst spells a number of times before exiling. Rinse and repeat, if you play Exorcist you'll be doing that a lot.
Attributes
From best to worst:
SPC and DOM
By far Heretic's best 2 attributes, you should always invest in both with as many points as possible.
PAT
Highest base attribute bonus makes it's a valuable dump stat and has good nodes at 150 and 200.
INT
Weaker base attribute but has valuable nodes and is important for some key items including 
Resonator Ring and 
Artificer's Shoulderpads. The nodes at 25, 100 and 125 out perform patience at equal levels.
EMP
Situationally viable, sub-optimal stat for bursting but has some nice nodes for accelerating pet leveling and is required to use the Falconer's Trust set items (eg: 
Falconer's Gloves) or 
Whiplash.
MAS
Points should only be invested in mastery for items but even then should be kept to a minimum. Mastery is very weak compared to the top attributes so every point spent in mastery should be seen as a loss of bursting potential. Invest in it frugally or even better not at all.
WIS
Mana regeneration from Wisdom is not worth it at all and borders on entirely useless. 10 wisdom is required for swapping to 
Anima Construct, but that is ideally gotten by equipping an 
Easymind Hat or a 
Concealing Shroud. If you don't have access to either item putting 10 points into Wisdom is fine, but that's the only time you should ever invest in this attribute.
Pets
Exorcist uses 4 different pets.
Archivist
Our primary pet. Archivist is the pet we use for the vast majority of our run and we often burst with him as well. He levels quickly and gives great bonuses to Evocation efficiency and profits which for good burst on fast runs. His boost to Evocation spells also works with 
Spell Focus, 
Holy Fervor and 
auto 
clicking 
spells as our primary method of generating excess Hallowed Clicks.
Anima Construct
A useful pet for medium and long length runs. Stronger at higher mystery levels thanks to his strong scaling with hero XP however it can take a substantial amount of time to level 
Golem to unlock Anima Construct. It's up to you to decide when to invest time leveling a Golem and Anima Construct for an extra burst of profit versus when to do higher frequency, shorter runs with Archivist.
Simulacrum
Only used in the longest and slowest Exorcist runs. Maximizes your mana sources but like Anima Construct can be slow to unlock without pet gear and an investment in empathy.
Spellhound
Useful only at the very start of a run to charge your spell sets. Shouldn't be used for more than 3-4 activations.