Farming the low level zombies in the Graveyard is an easy method of increasing the kill counter to obtain the Zombie Bulwark's defense bonuses. However, if you're capable of doing so with ease, farming the Crypt Ghouls in the Hub Crypts is a better alternative as you are simultaneously gaining more Combat XP compared to the Graveyard zombies. Either of these methods will require a lot of patience and dedication.
It has yet to be proven, but it's possible that using a Zombie grinder on your island to increase the kill counter for the Zombie Bulwark effect has been patched at some point during version 0.12.
Due to the fact that Revenant Armor doesn't boost your damage and Revenant Horrors are considered an easy slayer boss, a lot of people would recommend you to use a damage-oriented set instead of this, so that you can do Slayer Quests faster like strong dragon armor.
One of the best ways to farm kills for the counter is using any pet that does damage around you (for example Bal pet) and go afk in the goblin campfire in the Dwarves Mines.
It has to be proven, but the "Trolling the reaper" full armor effect should activate if you have one or more pieces of Reaper Armor on with Revenant Armor
In version v0.7.7, the Revenant Boots recipe was bugged, requiring an additional 16 Revenant Viscera on the bottom-right of the crafting recipe.
The Revenant Leggings used to be chainmail leggings and got changed to Diamond during the Reforge Update.
Despite the Tarantula Armor, a set comparable to this, being able to become Dungeons gear, this armor cannot. It is unknown if this will be changed in the future. This includes not being able to transfer the dungeon armor over by upgrading the Zombie Armor Chestplate into a Revenant Chestplate.