Blade of Selves gives an equipped creature myriad, creating temporary attacking copies for the opponents it was not originally attacking. In a multiplayer game, that can spread pressure around the table and multiply valuable creature-entry abilities. The Equipment costs two mana to cast and four to equip, so the payoff needs to justify a meaningful setup investment before the first attack.
Creatures with strong entry effects are attractive carriers. Gray Merchant of Asphodel can produce additional drain triggers as the copies enter, while Solemn Simulacrum can search for more basic lands. The copies are exiled at the end of combat, so they are temporary attackers, but value produced by their entry abilities can remain long after they disappear.
Myriad copies enter tapped and attacking rather than being declared as attackers. Their own abilities that trigger when they attack do not trigger from that entry alone. This makes entry triggers and combat-damage abilities better partners than simply selecting a creature with a powerful attack trigger and expecting each copy to repeat it.
Legendary creatures require additional care because the legend rule normally forces you to keep only one permanent with that name. Their entry abilities may still trigger, but the extra copies will not remain as a normal attacking army. Choose a carrier based on the value its copies actually provide, and remember that myriad scales with the number of opponents still in the game.
