History of Cornered Flakes

Cornered Flakes ("Collect the Rare tonic Flake reagents") is an Episode: Revenant triumph tied to Tonics. No source I opened describes the triumph itself; ProGameTalk's guide leaves its section as "to be updated" and the Slayer Baron list does not include it.

What is known

ProGameTalk lists four Rare Flake reagents: Volatile Flake (Episode: Revenant activities), Enriching Flake (earned in Onslaught Salvation), Tomb Flake (Tomb of Elders) and Reflective Flake (the Kell's Fall Exotic mission). The triumph likely means collecting each of these, but that is unconfirmed.