Guild Wars 2

i was curious; im currently working out a new build for my (wvw) necro (but cant access gw2 atm), if (for example) mark of blood hits 5 people; could i immediately follow up with epidemic on one of them to give the other four 6 stacks of bleeding instead of 3?

Correct.

One thing to note, Epidemic has a target for the spell and an AOE that hits 5 people, not counting the target.

sometimes im so stupid; when i read the descriptions it seemed like it wouldnt work… just re-read them and i dont see why it wouldnt "/

Yep, double the fun.