When this card declares an attack: You can target 1 face-up Spell Card your opponent controls; destroy it, and if you do, inflict 500 damage to your opponent. If you have no cards in your hand, except the turn this card was sent to the Graveyard: You can banish this card and 1 "Destiny HERO" monster from your Graveyard; draw 2 cards. You can only use this effect of "Destiny HERO - Celestial" once per turn.
Since it's attack can be pretty low in comparison to many commonly used level 4 monsters, you can increase its attack by using skills that give you the field spells, or bringing them in the deck. Joey's exclusive skill "Fields of the Warriors" gives you Sogen at the start of the duel, and Aster's skill "Destiny Calling" is for Dark City when your LP is at 3000 or lower.
A good way of sending Celestial to the grave is to use him as fusion material for cards like Destiny HERO - Dangerous, or use Mask Change to special summon cards like Masked HERO Anki. You can then use Celestial's effect from the grave to get some resources back.
guys funny thing happened to me today when I was playing PVP. My opponent used Relinquish and stole my D-Hero Dogma.I thought I was going to lose, then I just summoned Celestial and attack Relinquish using it's effect and destroyed Dogma making Relinquish attack became zero. I won. Just want to tell you guys that it works also on destroying effect monster cards (like Pumprincess) in spell & trap zone.