Arcane Melee can’t reduce the colored mana requirement of an instant or sorcery spell.

If there are additional costs to cast a spell, such as a kicker cost or a cost imposed by another effect (such as Thalia, Guardian of Thraben’s ability), apply those increases before applying cost reductions.

Arcane Melee can reduce alternative costs such as miracle costs.

The cost to cast an instant or sorcery spell with one generic mana in its mana cost will be reduced by {1}. For example, an instant spell with a mana cost of {1}{G} would cost {G} to cast.