Merificus is the main antagonist in Aralon: Sword and Shadow HD. He is a demon of another world with powerful magic that he uses to corrupt and hold sway over current King Owyn's mind as well as disguise himself as a human. He ordered Captain Renlyn Lordel's (each players' father) death as well as the capture of royal guard Gorak. He also personally murdered Queen Elenroh (King Owyn's wife), all because these people figured out that he was a demon and not of the world of Aralon.
Players encounter Merificus in two different forms - his human form, which is a disguise, as well as his true demon form. As part of the main quest of the game, players must obtain a magical object that will erase the spell over King Owyn's mind as well as Merificus' disguise. By obtaining this object and using it on Merificus, players will see him in his true form and cure King Owyn. In order to complete the main story of the game, players must defeat Merificus in his true form.
Merificus, in his true demon form, is one of the most difficult enemies to kill in Aralon. Aside from some of the swamp beasts (levels 41-42), Icefang (level 50) and Sheba (level 45), Merificus is the most highly leveled (level 40) in the game. One of the most difficult things to defend against is his ability to stun players. If he has time to use this ability, this player has found no defense to it (i.e. have it not affect you). The best way to defend against it is to use an attack that will stun him, hindering his ability to attack. These can include whirling blades as a warrior, judgment or sacrifice of blood attacks as a paladin, backstabs or vicious strikes as a rogue, ambush or lightning strikes as a ranger and fists of ice, shockwave or dazzle as a mage. Correctly timing these strikes so that Merificus is always stunned and in coordination with other character abilities, will ultimately allow players to defeat this antagonist. Once he has been defeated, players will be transported back to the Palace in East Callaheim.