Blade of Shared Souls

The copy effect here rewires when the decision gets made. Most persistent-clone creatures ask you to pick a target on entry and then hold that shape until they die; the "becomes a copy" clause on this Equipment fires on attachment and lasts only while it stays attached, which turns the choice into something you can revisit rather than lock in. That re-attachment window is the whole engine. The For Mirrodin! trigger hands you a 2/2 Rebel and staples the Blade to it immediately, so you get a copy selection the moment it enters: three mana into a duplicate of your best creature on the same turn, with no further investment required. Equip then lets you move the Blade onto a new host, and every move re-fires the copy trigger, letting you pick a fresh target each time. The self-generating body pays for the Equipment's own carrier while the copy rider does the work most clones do only once. Two caveats keep it honest: the copy only wants to be attached, so if the equipped creature is blinked or bounced the Blade simply falls off and sits inert on the battlefield until you equip it again (blinking the Equipment itself is what re-triggers For Mirrodin! for a free re-cast of the whole package). And the copy target must be a creature you already control, so the effect deepens your best threat rather than stealing an opponent's. It is a redirectable clone with a chassis that carries itself, which is a pairing the two lineages rarely share.