If you have 2 Aurora triggers and hit Deadbloom Predator first (playing it to enemy battlefield causing a pending showdown) then hit Whiteflame Predator second, does Whiteflame's trigger resolve before the showdown starts, and can it target Deadbloom?

Ruling: When you have multiple Aurora triggers creating a closed chain state, you cannot start a showdown while chain items are still pending. The Whiteflame Predator trigger will fully resolve before the showdown from Deadbloom can begin, allowing Whiteflame to target Deadbloom.

Sequence:

• Aurora trigger 1 resolves, revealing and playing Deadbloom to enemy battlefield (showdown becomes pending)
• Aurora trigger 2 resolves, revealing and playing Whiteflame Predator (its trigger becomes pending)
• Whiteflame Predator's trigger fully resolves (can target Deadbloom)
• Showdown from Deadbloom begins

Nuances:

• Whiteflame Predator cannot be played directly to the battlefield where the showdown will occur if you don't control that battlefield - it must be played to your base or a battlefield you control
• The showdown cannot start while any chain items are pending
• Permanents auto-resolve when finalized, which is why Whiteflame's trigger completes before combat