You’ll achieve management of a creature for every of the X Keigas you created and at most one battle will occur. You resolve the order.
When the Keigas enter the battlefield, every of them triggers the battle means, then the legend rule occurs. You need to select anyone Keiga you management (unique or one of many tokens) and the remainder die. This can be a state-based motion.
704.5j If two or extra legendary permanents with the identical title are managed by the identical participant, that participant chooses one among them, and the remainder are put into their house owners’ graveyards. That is known as the “legend rule.”
This occurs after the battle talents set off, however earlier than they enter the stack:
704.3. At any time when a participant would get precedence (see rule 117, “Timing and Precedence”), the sport checks for any of the listed situations for state-based actions, then performs all relevant state-based actions concurrently as a single occasion. If any state-based actions are carried out because of a verify, the verify is repeated; in any other case all triggered talents which might be ready to be placed on the stack are placed on the stack, then the verify is repeated. [..]
You’re left with one Keiga; the opposite X Keigas die and set off their demise means. Each the battle talents and these demise talents are ready to enter the stack.
State-based actions space checked once more and, if none apply, all of the triggered talents enter the stack within the order of your selection. You choose the related targets as you place every means on the stack.
603.3b If a number of talents have triggered for the reason that final time a participant acquired precedence, the skills are positioned on the stack in a two-part course of. First, every participant, in APNAP order, places every triggered means they management with a set off situation that isn’t one other means triggering on the stack in any order they select. (See rule 101.4.) Second, every participant, in APNAP order, places all remaining triggered talents they management on the stack in any order they select. Then the sport as soon as once more checks for and performs state-based actions till none are carried out, then talents that triggered throughout this course of go on the stack. This course of repeats till no new state-based actions are carried out and no talents set off. Then the suitable participant will get precedence.
Then the stack begins resolving. Should you selected to maintain a token Keiga for the legend rule and the opposite creature continues to be being managed by your opponent, that battle can occur. No different battle can occur as a result of the Keiga it originated from might be useless to the legend rule.
701.12b If one or each creatures instructed to battle are now not on the battlefield or are now not creatures, neither of them fights or offers injury. If one or each creatures are unlawful targets for a resolving spell or means that instructs them to battle, neither of them fights or offers injury.
So in complete: Should you created X Keigas with Aggressive Biomancy, you’re taking management of as much as X creatures as a result of X Keigas will die to the legend rule. Should you saved a token Keiga for the legend rule, it should battle the opposite focused creature if it is nonetheless managed by your opponent. You select the order of management modifications and the battle.
