You can win without it, but adding it offers another way to go infinite
Put it onto the battlefield as a creature token
Primary: Blue Secondary: Red As blue and red are the spell colors (they have the highest percentage of spells versus creatures), they are the two colors that can get instants back
Maybe Feather, the RedeemedFeather, the Redeemed will have the best time surviving the damage and flipping this thing over to start dishing out more damage
Creatures that make mana (mana dorks), artifacts that make mana (mana rocks), Rampant GrowthRampant Growth-type effects, "rituals" like Dark RitualDark Ritual, cards that make Treasure tokens
Probably the most common cost for an activated ability is to pay some amount of mana, so most instances of paying mana are to activate an ability