White creatures usually have lots of keyword abilities like flying, first strike, double strike, lifelink, or vigilance, and as such it makes sense to enhance those
Enlightened Tutor became the backbone for many combo-based decks because it could fetch most pieces of combo-based engines, including at various times Aluren, Enduring Renewal, Opalescence, Cadaverous Bloom, Pattern of Rebirth, Icy Manipulator, and Winter Orb
This can often have a game ending effect, all the dragons and all that, but is still a non-permanent card (thus uncheatable) in the deck that costs 7 mana
Overwhelming Stampede is the king of these one-time noncreature spells
Keep sacrificing the Myr Battlesphere and at least one Myr token to recur them endlessly, giving you infinite mana, tokens, and death triggers
Whether youre looking to build a typal deck or just build around a powerful commander, merfolk commanders have options for you