Erroll de Wardes is fought briefly during the scenario of Sylvain Dieudonné. The fight is unwinnable, as Erroll is presumed to have unlocked all three of his advanced spells, and will use them liberally, often pausing to drain away Sylvain's life and magic every few attacks with his powerful Resiary. If his MP is completely depleted, Erroll will drink an Elixir, fully restoring both his health and magic.
The battle ends whenever Sylvain is defeated. If he manages to deplete two-thirds of Erroll's health, it will be revealed that Erroll was not fighting at full strength, and it will end with Sylvain falling to his Meteor spell.
As a boss, Erroll has the same stats he does at level 99, though Sylvain will likely only be at level 40 or so when facing him. He equips the Magic Sword Caladcholg for the duration of the fight. He begins the fight by blowing Sylvain away with a defencive casting of Blossom X, and can also cast Halt X, Champagne X, Nurse X, Wrath X, Force X, and Ember X almost instantaneously. When attacked directly, Erroll tends to counter with a long, wide-reaching, and powerful combo that is also quite slow, but still difficult to avoid or defend against. If Sylvain leaves himself open, Erroll will freeze time and launch a powerful combo that can defeat Sylvain in one casting.
Every fourth attack is the advanced spell Resiary, which is highly-difficult to dodge and which drains a large amount of HP and MP with each casting. When a third of his health is depleated, Erroll will begin to cast spells with greater frequency and will begin to enchant his combos with Resiary and cast a regenerative effect upon himself. Once two-thirds of his health are depleated, Erroll will cast the advanced spell Meteor, which will normally be impossible for Sylvain to survive at the intended level. As the spell is part of a storyline event, it will continue past its normal duration until Sylvain is defeated.
Second Playthrough and OnwardsEdit
Although Sylvain canonically loses the fight, it becomes winable during a second playthrough. During this fight, Erroll will not cast Meteor, but will instead use the spell Blossom XX with increasing frequency. If Erroll is beaten, the scene in which he reveals that he was not fighting at full strength will play again, and Sylvain will be knocked unconscious by the Meteor spell as a part of a cutscene.