Thinking of doing a 2H Sword run with greatshield talisman, regen talisman and bestial vitality to be able to block with my sword and regen the chip damage.

This spell is almost a requirement for low to mid level co-op (under LVL 80 or so), as it boasts very low FTH requirements (just 12 FTH!), is easy to get, and provides a ton of HP per FP per cast. This lets you conserve HP flasks while running around in the overworld, where the slow heal rate doesn't bother you much because (1) you have less health overall (2) enemies don't hit as hard and (3) there is a lot of down time in between your taking hits (hopefully). Even if you have access to the FTH boons (which require 24 FTH or more), Bestial Vitality is still worth running, as it is vastly more FP efficient then the Boon spells.

It gets less useful as enemies hit harder and HP bars grow, but is still useful / worth slotting even up to 60 VIG.

This is quite good in coliseum duels, for those times when opponents decide they want to admire your armor instead of pressuring you.

this plus flame cleanse me sound incredible for the colosseum, if someone procs scarlet rot on you they will probably target someone else in the colosseum since you're basically dead already, using this time to go away, cast flame cleanse me and then this, then boom ,you're back in the fight and you're only down 32 fp, worth the 2 faith you have to lvl up to get both of these

hard carry spell

This plus bloody slash for an early game bleed build or arcane/faith.

I wish it was affected by the bestial incantation bonus from the clawmark seal and cinquadea

Maxed flask is 810 hp, so even late game this is worth 3/4s of a flask at 600 hp, so even late game definitely worth it for boss fights as you can usually get an extra buff in during the fight

Pair well with (dual seppuku) (don't judge me)

Very nice with Ritual Shield Talisman against anything that hits hard.