Playing a pick-two draft on mobile (I've clicked "capture logs" a few times, but nothing happens), and I went to combat with a ghalta in play and ferocity of the hunt in hand. I had a lethal swing, but waited for my opponent to declare blockers before deploying the FLASH speed ferocity of the hunt. I had 6 mana open and my opponent didn't have anything preventing flash-speed interaction in play. After opponent declared blocks the game immediately went to how I assign damage across the three blockers. I thought that was weird, but figured I could respond after pre-assigning damage. Nope, the game went right through with the action without allowing me to cast the flash-speed enchantment. I lost because of this error.