You’ll acquire management of a creature for every of the X Keigas you created and at most one combat will occur. You resolve the order.
When the Keigas enter the battlefield, every of them triggers the combat potential, then the legend rule occurs. You must select anyone Keiga you management (unique or one of many tokens) and the remainder die. It is a state-based motion.
704.5j If two or extra legendary permanents with the identical identify are managed by the identical participant, that participant chooses one in every of them, and the remainder are put into their homeowners’ graveyards. That is referred to as the “legend rule.”
This occurs after the combat talents set off, however earlier than they enter the stack:
704.3. Every time a participant would get precedence (see rule 117, “Timing and Precedence”), the sport checks for any of the listed circumstances for state-based actions, then performs all relevant state-based actions concurrently as a single occasion. If any state-based actions are carried out on account of a examine, the examine is repeated; in any other case all triggered talents which are ready to be placed on the stack are placed on the stack, then the examine is repeated. [..]
You might be left with one Keiga; the opposite X Keigas die and set off their loss of life potential. Each the combat talents and these loss of life 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 potential on the stack.
603.3b If a number of talents have triggered for the reason that final time a participant acquired precedence, the talents are positioned on the stack in a two-part course of. First, every participant, in APNAP order, places every triggered potential they management with a set off situation that isn’t one other potential 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. In case you selected to maintain a token Keiga for the legend rule and the opposite creature remains to be being managed by your opponent, that combat can occur. No different combat can occur as a result of the Keiga it originated from will likely be useless to the legend rule.
701.12b If one or each creatures instructed to combat are not on the battlefield or are not creatures, neither of them fights or offers harm. If one or each creatures are unlawful targets for a resolving spell or potential that instructs them to combat, neither of them fights or offers harm.
So in whole: In case you created X Keigas with Aggressive Biomancy, you are taking management of as much as X creatures as a result of X Keigas will die to the legend rule. In case you saved a token Keiga for the legend rule, it should combat the opposite focused creature if it is nonetheless managed by your opponent. You select the order of management modifications and the combat.
