Sceptre: [+4lvl to Minions] VS [+2lvl to Minions + 50% allies damage]

Which is better?

entirely depends on the build.

build is witch: arsonists + srs

what I mean is, it depends on how much increased damage your allies already have, because increased damage is additive

if you don't have any increased damage, 50% increased damage basically means 50% more damage

if you already have 100% increased damage, that's 200%, and going from 200% to 250% is 25% more damage

so the value of increased damage mods become less as you get more of it

After campaign +4LVL, especially for SRS, earlier, increased damage. At the beginning 50% Allies damage is stronger because you don't have many increased damage from passives and gem lvls mean more later on, not only for damage but also for minion life, accuracy.

While the above posts are true in theory, the reality is that the crossover is so small you might as well ignore it - if you're playing a minion build you will (sooner rather than later) be at a spot where +4 minion is far better than 50% allied damage, which is also punishingly small in range.

Put on the +4 minions, forget the other one exists, and be happy. The math might be slightly outside your favour for an extremely small amount of time for minions that hug your arse.

Thanks! Now it's much clearer to me.