You can't cast Divergent Transformations without two target creatures. If a targeted creature becomes an illegal target for Divergent Transformations after it's been cast, its controller won't exile or replace that creature, but the other creature is still affected.

If two players' creatures are exiled this way, start with the player whose turn it is. If that player controlled a creature exiled this way, that player follows the process on Divergent Transformations to replace it. If not, proceed to the next player in turn order. Repeat until the players who controlled the exiled creatures have each replaced those creatures.

If one player's creatures are exiled this way, that player repeats this process twice.

The two creatures that are put onto the battlefield are put onto the battlefield sequentially. Triggered abilities of the second won't see the first enter the battlefield.

Any abilities that trigger during the resolution of Divergent Transformations will wait to be put onto the stack until Divergent Transformations finishes resolving. An ability that triggers on the first creature entering the battlefield may target the second creature and vice versa.

If the controller of a creature exiled this way has no creature cards left in their library, that player reveals the cards in their library, then shuffles it.

Causing an opponent to lose the game after you've announced that you're casting a spell with undaunted and determined its total cost won't cause you to have to pay more mana.

Effects that reduce what you pay to cast a spell don't affect its mana value.