If anyone is having trouble opening the door to Vendrick you need to be a human and not hollow.

so ez with vanq seal lmao

Sadness ahead

I give ds2 alot of **** but I will always give credit where it is due. The entire crown sub story is extremely cool and feels genuinely rewarding. Vendrick is also a cool character to boot.

How to kill easily with just the 1 Giant Soul from Black Gulch (or none): bleed him to death using a Bandit Knife.
With a bleed infused +10 one and Crest of Blood, Vendrick bleeds in 4 hits. Wait 5-6 sec, then bleed him again. To be safe and have fast stamina regen, I took my highest stability 100% block shield, Life Ring+2, Second Dragon Ring, Cloranthy Ring+1, soulgems, REPAIR POWDER, and was naked with 50 vigor.

Like the guy who posted below, I used bleed on Vendrick with only 1 giant soul. It took me about 6 deaths to learn his moveset, but using a notched whip made it fun because I literally whipped his ash. I had full havel set, which helped because I could tank at least 1 and then heal up. Bring a repair powder or 2 and most importantly DO NOT panic heal after taking a hit. Wait till you've baited another attack from him first. He isn't that hard of a boss, but he can get in your head because of his insanely high dmg. Just circle close to the side of his left leg and you'll make him your bich in no time.