These cards can be replaced with Groundskeeper, Mark of the Wild, Wild Growth. The replacement takes place from left to right (i.e., if the player replaced one card, they will receive Groundskeeper regardless of whether Enchanted Raven or Feral Rage was replaced).
Mannoroth was the barbaric leader of the pit lords when Kil'jaeden recruited them. When Archimonde was placed in command of the pit lords, he recognized Mannoroth's value as a brutal, bloodthirsty fighter and made the pit lord his second-in-command. Mannoroth helped lead the Burning Legion in assaults on countless worlds, and led the first invasion of Azeroth. His ruthlessness and vile cunning made him into one of the favoured lieutenants of his masters, Archimonde and Kil'jaeden, the champions of the Burning Legion. He is known as "the Destructor" and "the Flayer".
After Thrall reclaimed Hellscream, Mannoroth lured them into the craters formed by the falling infernals, where he hoped to kill Thrall and re-enslave Hellscream. Thrall confronted the demon lord in battle pouring all his strength and hatred for the demon into one powerful blast with the Doomhammer. Mannoroth applauded the effort and revealed that it had caused only slight scarring of his wing. He then tossed the young warchief against a cliffside with a powerful charge, knocking him out cold and leaving only Hellscream. Mannoroth reminded Grom that he owned his body and soul and gloated that the blood curse could never be broken.
Hellscream then faced the choice between giving into the demon corruption once more or resisting and saving Thrall, and indeed his entire race. Refusing to accept that the orcs were cursed forever, he chose his kin. In a heroic last stand Grom slipped past Mannoroth's defenses and sliced open his chest.
Mannoroth was thus slain by his greatest creation and most favored pupil, Grommash Hellscream — a fitting irony, some might say. The demonic fires erupted outward, destroying the astonished Mannoroth and mortally wounding Hellscream.