Dark soul wiki :
It is sometimes recommended to attempt the Four Kings boss fight solo. Unless the summoned group has efficient DPS output (damage per-second), the extra health can make it take longer to kill each boss, sometimes causing the player to get swarmed by more kings as they spawn. This is especially the case when summoning the NPC Witch Beatrice, whose presence typically only makes the fight harder.
Du coup sauf si ton build est à chier, tu y arrivera mieux solo. Git gud