Does bosses get tougher when there are more players fighting it?

[RADjäger]

I was fighting the spider queen solo and died, when i return to it, there was another player and the fight was much tougher than earlier and more spawns too.

[Suzaku]

More health, and more spawns. Yes, co-op can sometimes be harder than solo.

[YomaBlood]

Yes, Bosses scale of number of players, theyll have more summons, more AoE spawn mechanics and such. for ex. the boss that spawns the shadows, shell spawn an additional set of shadows per players engaged. Only real benefit to group kill bosses is the ability to retreat to heal up without having the fight reset. You can tag team and all bosses turn into cheese

[Aapjuh]

Think it's surprisingly well balanced, some bosses are easier, some are harder. Both when solo or in a grp that applies.

As a solo i notice some bosses are quite hard when solo, but steamrolled when randoms show up. specially bosses where the split attention brings benefits.

an example would be quincy or behemoth vs witch or spider.
when solo quincy or behemoth charge ability is always focused on you always keeping you on your toes, but in a group 1 of you can hang around without worry slinging spells etc.
the opposite is true for witch or spider, when solo 2 adds will chase you and its manageable or can be ignored/worked-around, when in a grp 4 adds could attack 1 player which becomes threatening.

[Akadai]

The spider is probably one of the worst offenders when it comes to co-op battle. The amount of adds it spawns is stupid. Typically all the adds don't split equally either, making it even worse. If someone dodges/stealths, then all of them will direct their attention toward one player, usually too much to handle. After several attempts at this boss, most of us ended up soloing it later with greater ease

The spider has been so far the hardest boss for my group of friends to do together and was cause of great frustration