In addition to making it easier to Synchro Summon a Monster, this card's effect can be used like a one-time "Mausoleum of the Emperor" to let you Normal Summon a high-Level monster from your hand without Tributes.
You can combine the above strategy with "Cost Down" to summon a really high-level monster like "Yubel" from your hand.
If you have enough lifepoints, decrease the level of one of your monster down to one. Then equip the selected monster with "Opti-Camouflage Armor" for a one turn direct attack.
If you selected a Normal monster, equip it with "Amulet of Ambition" before decreasing its level with this card. In that way, the selected monster will get a major power boost when it attacks an opposing monster.
If your field has a high number of Normal Monsters (up to five monsters), decrease one Normal monster down to level 3 before equipping the selected monster with "Sword of the Soul-Eater". At that point, the selected monster will gain a major power boost, depending on the number of monsters that you tribute for the sword's effect.
Use this card to allow a high level monster to attack even while cards like "Gravity Bind" are in play.
Use this card in an "Alien" deck to summon "Alien Overlord" without tributing a monster.
You can summon "Dark Simorgh" for only 1500 Life Points. If you do this early in the game and have a way to protect it, like "Destruction Jammer" or "Starlight Road", you can prevent your opponent from defending themselves and maybe get an early win.
This card can greatly increase your chances for an Xyz Summon by adjusting the Level of 1 of the monsters in your Hand.
This card can lower the Level of "Victory Dragon" to 4 or lower, making it so those 3 Tributes are not required.