Predecessor Builds > Revenant > Revenant - ADC

Because you get 1% bonus damage for every 10% crit chance from Rev's passive, and the fact that his 4th basic attack always crits, stacking 5 items with crit is mandatory, and 6 items works too!
For crest you should go with Witchstalker, with an option to go Ortis.
Vanquisher is always first item, followed by Imperator to boost 4th basic damage early. Next is Demolisher and Penumbra to get penetration on-line, and lastly, Nuke Rounds and Terminus to finish. Ashbriger for cooldown reduction or Tainted rounds for anti-heal.

Open the fight with Scar > Obliterate (E>Q) combo, then just blast people like they owe you money. Remember that you can reload while Q is casting, so 4 shots > reload starts > Q > shoot. That helps keep your dmg from falling off while you reload, at least when Q is available. Always use E before Q when you can, its pointless to use E after Q.