Most veteran FromSoftware fans know that enemies get some pretty substantial buffs whenever you call another player into play. This is mainly to prevent the boss from being too easy by increasing its parameters to make sure it is still a challenge if multiple players fight it at the same time. Until today, we didn’t know how powerful these buffs were. Now we know.
This new information comes from Illusory Wall. According to his information, bosses get different buffs depending on how many people you have summoned to your world. If you only summoned one, the bosses will receive a 60% increase in their health, as well as a 50% buff to their resistances.
If you summon two other players to your world, the buffs will increase even more. The boss will receive a 130% health boost, as well as a 100% buff to his poison resistance and a small 10% damage buff. Other resistances will remain at 50%, although Illusory Wall finds this a bit odd and thinks it could be a potential bug/oversight that could be fixed in the future.
These buffs even apply to normal enemies, although they are much less than those of bosses. Most normal enemies will get 25% health and 50% resistances, although this can vary.