Door of Destinies turns a sequence of creature-type spells into a lasting team boost. You choose a creature type as the artifact enters, then each spell you cast of that type adds a charge counter. Your creatures of the chosen type get +1/+1 for each counter, allowing a deck with a concentrated type to grow its entire army as it continues casting spells.
Elf, Goblin, and other low-curve creature-type decks can build counters by casting several spells in one turn. Beast Whisperer or other cast-based draw engines help keep that sequence supplied in decks with the appropriate colors. Tokens of the chosen type receive the boost, giving token makers a useful role even though simply creating those tokens does not add counters to the Door.
The cast requirement is important. Creatures entering through reanimation, blink effects, or token creation do not trigger the Door merely by arriving. If your deck primarily puts creatures onto the battlefield without casting them, a different anthem may produce value more consistently. The artifact also begins without charge counters, so it needs follow-up spells before it improves combat.
Counters remain on the Door after your creatures are removed, helping a later wave enter as larger threats. Removing the Door itself takes away the bonus immediately, which can change combat or leave damaged creatures vulnerable. It fits decks that expect to cast their chosen type repeatedly and want the accumulated investment to support both the current army and future rebuilds.
