Incarnation is a gamemode that was introduced during the days of Confrontation 1.0, updated in 2.0 and later reenvisioned as Dogs of War.
Incarnation involved bringing a character along with a small group of figures on a multi act adventure. The Act cards are referred to as Scenario Cards. There were also Confrontation 2 / Incarnation supplement card packs called the Travel Journals. Through their journey the Incarnate is able to aquire Experience Cards through means of performing various feats in battle or by spending experience points gained from combat, allowing them to wield said experience boons at a reduced cost. In the Incarnates search for their soulbound Elixer, they must eventually confront their Shadow, a powerful enemy controlled by the opposing player, the "shadow player".
An "Incarnation" ability was written which allowed making any non character into a character with all its given advantages, thus doubling their original AP value. A character could also gain experience points by playing regular games of confrontation, and those whom had acquired strength from experience would be able to be brought onto the epic stage which is Rag'Narok.
A rule booklet for this gamemode can be found in the Rules section of the wiki.
Because of Rackham's decision to ban the use of all Incarnation related Scenario cards moving to Confrontation 3, along with the rules changes, it makes it difficult to attempt to use them. Nevertheless, this can be done indiscriminately of requiring a rules setback by only implementing certain ruless that might seem necessary to cards you plan to use. However, for those curious, guides and compilations showing the differences can be found in the Game Aids & Resources page.