The Grimoire got introduced with Whispers in the Walls (U35) and it also Includes some pretty unique support mods
It can kill easily and start giving the Canticles buffs if u strip before killing small fries, I suggest grouping for the Invocation buffs with either [Nautilus] , Larva or Ensnare subsumes.

If there's any complains or suggestions for improvements feel free to comment.

Keep in mind you can only use 1 Invocation and Canticle at a time.

You can use the following Invocations to buff your abilities or energy
-Netra Invocation: Alternate Fire increases Ability Efficiency by 4% for 20s for each enemy hit. Stacks up to 15 times.

-Vome Invocation: Alternate Fire increases Ability Strength by 4% for 20s for each enemy hit. Stacks up to 15 times.

-Ris Invocation Alternate Fire increases Ability Duration by 4% for 20s for each enemy hit. Stacks up to 15 times.

-Xata Invocation: Alternate Fire grants 1 Energy Regen/s for 20s for each enemy hit. Stacks up to 10 times.

And the following Canticles to Buff your allies or do a little bit of stripping
-Fass Canticle: Killing enemies grants Allies in Affinity Range 40% Shield Recharge Rate and -28% Shield Recharge Delay for 15s.

-Khra Canticle: Enemies have a 12% chance to drop a Universal Orb on death.

-Jahu Canticle: Killing enemies reduces the Armor and Shields of other enemies within Affinity Range by 5%.

-Lohk Canticle : Killing enemies grants Allies within Affinity Range +30% Fire Rate for 15s.

Mod choices
You can mod this weapon like a normal crit pistol including the following stats:

-Multishot: pretty mandatory stuff

-FIre rate: with unlimited ammo you need as much fire rate as possible

-Crit mods: Primed Pistol Gambit and Primed Target Cracker for some sweet CC and CD

-Viral mods: u can do 60/60s or use the 90%s.

U can replace Anemic Agility with whatever suits your fancy, even PHC or GC

Arcanes
Use whatever you want to use, I'd personally go with Secondary Merciless or Cascadia Overcharge, you can also prime with Secondary Encumber or use Secondary Outburst if u run a build like an initial combo Incarnon