You may pay and tap four untapped creatures you control with flying rather than pay this spell's mana cost.
Flying, lifelink
Other creatures you control with flying have indestructible. (Damage and effects that say "destroy" don't destroy them.)
Flood the board with flying creatures, then drop Sephara (often for just ) to make your whole air force indestructible while gaining life off her lifelink. You win by swinging with a wide, hard-to-kill skies army that ignores board wipes and most removal. Early game ramps and builds the flying token base; mid-game Sephara locks the board and turns alpha strikes into game-enders.
Grants the entire flying team indestructible, surviving most board wipes and combat
Alternate cost lets you cast a 7-drop for once you have four flyers
Mono-white keeps the mana base painless and consistent
Lifelink on Sephara plus a wide board stabilizes against aggro
Heavily commander-dependent; without Sephara out the deck is fragile to wraths
Indestructible doesn't stop exile, -X/-X, sacrifice, or bounce effects
Mono-white struggles with card advantage and ramp compared to other colors
Vulnerable to fliers/blockers and to Cyclonic Rift-style mass bounce