Strategy: Single Player vs Multiplayer
The difficulty scales based on the number of players in the game. They do this by increasing monster life and damage by a certain percentage for every additional player. The table bellow shows these percent values.
|Life increase per additional player||75%||85%||95%||110%|
|Damage increase per additional player||0%||5%||10%||15%|
As you can see, each additional player in Normal, Nightmare, and Hell difficulties will lower the monster’s effective life since the added life is less than 100%. This means that a group of players will be able to kill monsters significantly faster than someone doing it solo. This does not hold true for Inferno difficulty. It will actually take longer to kill monsters in Inferno with more players.
So why would you party-up in Inferno difficulty? The monsters’ effective damage is reduced! As long as the damage being done by the monsters is spread more or less evenly across each player’s health pool, then the group will survive significantly longer than a solo player.
In all cases, playing as a cohesive group will increase killing speed, allowing for the most efficient magic finding and XP grinding.