Keeper's Recipe?
I got one in Mari’s chest, another in lair chest.
Sylvari Guardian. – Dragonbrand.
You get the bonus chest everytime you attempt marionette w/ at least one chain severed. You can loot the chests in Scarlet’s Lair as many times as you wish so long as you have enough cyphers.
I got a Zealot’s recipe from a V bonus chest. Odds are Keeper’s can appear from one too.
The bonus chests are per run, but vary based on how many chains are severed. The ground chest after Mari is daily. The chests in scarlet’s lair can be opened as many times as you have keys.
I got mine for keeper armor from a wurm chest
Personally I like the idea behind sub classes ~ quoted from Chris Whiteside