Nether core rush

I would suggest If the game mode is not on Hard or Hardcore to make this event not occur as to ensure more relaxed game play for those who want it. If a Nether portal is struck by lightning it transforms it into a Nether Core, where the Nether would leak into the Overworld with a boss bar like timer. In  this event the terrain would transform more and more while spawning Nether enemies and spawners. The players would have to destroy the Nether core before the timer is up signaling the completion of the structure and summoning a new boss perhaps even an the old Blaze knight (assuming that is what it's called) enemy from the mob vote which would then be guarding the Nether core. Once the Nether core is destroyed however the blocks will turn back to normal with any added blocks disappearing, mobs would start to take damage or transform due to any Overworld effects, and the portal will either return to normal or become ruined (replace some Obsidian with Crying Obsidian and keep some surrounding Nether blocks) showing the Nether's retreat and reverting any changes to the world. As reward for breaking the Nether core you would be rewarded with loot similar to a combination of Bastion's and Nether fortress's loot.

Thank you for listening to my idea and taking time out of your day to do so. I hope you have an amazing day.