Finley’s Hero Power only costs one mana on Heroic (give a friendly minion Divine Shield and Rush), and the “plot armor” fake Secret he casts on turn one in the Story mode is replaced with the Unite the Murlocs quest. Other than that, this encounter is basically identical to the normal version, and any deck which can ignore the board will get things done. A standard Holy Wrath Paladin build will be just fine for you – just keep in mind that Finley’s assortment of random Murlocs can generate a Coldlight Oracle, potentially ruining your moment of triumph!