This one is for real homies only.

Use with [Energized Munitions].
The mechanics of the alt-fire means you get to alt-fire 4 times with Energized Munitions before needing to reload.
[Mag]'s magnetize may help with triggering Wild Frenzy refund.

PP-Round gives more than primary merciless due to magazine size - 465% damage increase (letting you skip serration and damage mods). Damage is not needed with PP-Round. Trigger PP-Round by alt firing once.
Overframe does not add PP-Round damage to calculation.
Actual damage should be around nine hundred thousand burst if my math is incorrect (which it is).

More math - Tainted Mag + PP-Round gives 465.5% extra base damage, as well as more bullets for an easier Wild Frenzy trigger. Serration + Primary Merciless is a 525% conditional and difficult damage increase that also makes triggering the ammo refund on Wild Frenzy incredibly difficult - requiring you to kill multiple enemies before getting to that amount, and for a short period of time.
Note - Running Serration + PP-Round gives 526% damage but makes your [Grakata] salvo last a lower amount of time (although it may make killing easier).

Wild Frenzy doesn't actually increase your tooltip firerate by 400%, rather it sets the firerate from base [Grakata]'s 20 to 80. Base [Prisma Grakata]'s ~21 firerate does not get set to 84, due to how the mod is coded. Instead, you get the base 80.
Decreases to fire rate do not impact the alt fire from Wild Frenzy, meaning Critical Delay only provides a buff on alt fire. Same interaction with Vile Percision.
Reloading is still required after firing, as Wild Frenzy refund only returns to ammo pool.
Wild Frenzy also disables aiming, preventing benefits from mods such as Bladed Rounds.
The usual 'Viral Mumu' build is ignored due to not being able to kill an enemy in sufficient time to trigger Wild Frenzy's ammo refund. Instead, Galvanized Aptitude's damage is considered, hence the multiple statuses.

Having a Riven helps, look for critical chance and status chance, or more status effects, and replace accordingly.
Use with a primer if possible. Otherwise, consider swapping Galvanized Aptitude with another mod of choice.

5 Forma without Vile Percision.

Have fun!