Use this card on a Level 7 or higher monster that has no summoning restrictions: if the result is 1 you can Special Summon it from the Graveyard later, if the result is 2-6 you will reduce the number of required tributes.
If using this effect with "Sacred Phoenix of Nephthys", you can either reduce its Tribute cost, or send it to the Graveyard (if you roll a 1) and Special Summon it later in the game with "Call of the Haunted" in response to an opponent's monster destroying effect (or effect targeting your face-down "Call of the Haunted"), so you can still have a monster on the field, while at the same time wipe away all Spell Cards and Trap Cards. The worst you could roll in this case is just a 5 or 6, which still makes Sacred Phoenix easier to Summon by 1 less Tribute.
This card can be great for any Synchro Deck as long as the result is not 1. However, you should make sure you can still Synchro Summon no matter what the result is.
As a last effort, you can use this card on a lower Level monster, if you don't have a higher Level, to change its Level to 5 or 6 and then use "Soul Exchange" or gain control of your opponent's monster to Tribute. This also works if you want to use "Hardened Armed Dragon" to protect a lower level monster.