I really like the mode, but here are some changes I'd make:
-Bardle Royale: Nocturnal edition
-Sleigh push: Attack/Defend
1) On-fire status feels too strong. I understand, and agree, that people getting a lead should be rewarded. But when combined with a healing/shielding support, an on-fire hypercarry becomes anti-fun to play against. Simple suggestion: Tone down the damage increase a bit.
2) The mode itself already highly favors the side that is behind. Now, add the Nocturne ult effect, and you'll end up with a stalemate. The enemy will bunker down to their corner in a brush, wait for your team to come, and take you out. Make so there are some gaps in the Nocturne ult: 5s of it on, 1s of it off etc.
3) Change the Veigar's/Teemo's pathing, so that it doesn't go under the turret of the jungle. Once again, the winning team is punished for doing well with a turret that can't be taken down. And if the enemy team has somewhat good comp, the Teemo/Veigar won't be coming out once gotten there. You are forced to towerdive a 5v6 under a turret that can't be destroyed.
4) A team shouldn't win an event by doing nothing. I'd take out this variation completely.
5) Make it, that URF is never the first event. Or increase the amount of bans. Make it so, that picking an URF champ is a gamble, rather than forcing people to spend their bans to champs that aren't exactly ban-worthy, but can't be left open due to the mode.