During your next Standby Phase after this card was destroyed by a card effect and sent to the Graveyard: Special Summon this card from the Graveyard. When you do: Destroy all Spell and Trap Cards on the field.
The most common way to Special Summon Sacred Phoenix of Nephthys is by using Hand of Nephthys. By using this card combination, you can immediately summon it and you can destroy 1 of your opponent's monster.
Another way to Special Summon Sacred Phoenix of Nephthys is by using Fire King Avatar Yaksha or Fire King Island's effect. Both of them has the capability to destroy Sacred Phoenix of Nephthys from your hand. By doing this, Sacred Phoenix of Nephthys will be special summoned on your next Standby Phase and it will destroy all Spell and Traps on the field. You can use cards such as Murmur of the Forest, Gravelstorm or Magic Reflector to prevent Fire King Island's destruction due to Sacred Phoenix of Nephthys' effect, so monsters in your field will not get destroyed. You can also use the second effect of Fire King Island, which can be used to Special Summon Sacred Phoenix of Nephthys from your hand if you don't have a monster in the field.
Wtf? Pot of greed in a 20 card deck? You wanna get OTK'd? They would be decks with almost 100% win rate like tea burn and even in a 40 card deck its too strong! Use your shard of grees and stop complaining about decent cards
When "Fire King Avatar Yaksha" get destroy on the field he can *DESTROY* "Sacred Phoenix of Nephthys" in your hand. So the start of your next turn, you get 2400 attack monster for free. And it also destroy all spell and trap for free.