Its simple they are the most agile which makes them the best relic holder.... And as for the other two it goes like this. Hunter 1 grabs relic. Hunter 2 pops golden gun runs down clears the adds and the relic holder cleans up what's left( only necessary on the jungle side due to Minotaur). Meanwhile hunter 3 pops his golden gun and one shots the first 3 oracles. Relic holder cleanses before the last oracle then runs out to the center platform and gets 3 or 4 relic supers off on Atheon before throwing up the shield for everyone else.

Golden gun the oracles.