Does difficulty scale with party size?

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Malice wrote:

Parties

The maximum party size is 6 players.

Effect on monsters
Monsters gain 50% extra life for each additional party member after the first. For example, against a party of 3 players, monsters have double life.
The original life amount is used for the purposes of determining the length of stuns and status ailments from elemental damage - this means monsters will not be harder to stun/ignite/etc. when fighting in a party.

Effect on loot
Each player in a party after the first gives the equivalent of +50% item quantity modifier on drops. So a party of three will see twice as many drops as a lone character.
Increased Item Rarity & Quantity modifiers are only counted from the player who lands the killing blow.

Effect on experience
Players in a party gain less experience for each monster kill than if they were alone. For the full experience formula, see the level scaling section above. Only party members actually in the instance count toward getting XP. If one member is in town he gets no XP.
Experience is only shared with other players who are near you (roughly two screens). Monsters are still made harder by players elsewhere on the level.

Monsters give +75% base XP for every party member after the first.

Effect on flasks
Only the character landing the killing blow on an enemy will gain flask charges. The same is true for all +life and +mana gained "when you deal a killing blow" modifiers.

Flasks have a +75% charge recovery bonus for each party member after the first.