While I highly doubt that anything would or could happen with the experience event part of the championships happening in less than 24 hours, I thought it was worth putting out there now, as I expect the event will highlight some of the issues here.
Right now, the Underworld has a single entrance through Azdun that always places you in the same location in the Underworld proper. This makes the Underworld extremely easy to reinforce and secure - the last time there was serious fighting over it, in the 852 games, we saw ret+totem+worldburn used as the dominant strategy to hold it, and I expect we're about to see the same thing done again. The result is that it's pretty unfeasable to take the Underworld from a group entrenched there, at least without the overwhelming numbers needed to fight through smacking a totem head-first in ret and worldburn, making it one of the most defensable positions in the game.
This, in a word, sucks. The Underworld ends up being very important in any sort of large-scale hunting event, and is only going to be moreso this time around with the experience boost it's been given. But rather than that leading to any kind of active, dynamic fighting, the go-to strategy will always be extreme entrenchment. This is Achaean combat in one of its least fun incarnations, where an entrenched group has a nearly overwhelming advantage. It also seems to undermine the justification for giving the Underworld experience boosts in the upcoming event. That was done on the grounds that the Underworld was one of the most dangerous places to hunt, but with how easy it is to defend it's actually much safer than hunting on mainland sapience, in my view. So long as you have a moderate force guarding the entrance, it's hard to think of a spot safer from getting ganked.
This could be hugely mitigated simply by giving the underworld another entrance, or another place the root could drop you. Alternative solutions would be to prevent propping totems, or woldburn all together (which there could be plenty of lore justification for). The resulting fights would be substantially more fun, and the resulting winner of events like this might not just be whoever gets set up first.
I'd love to see this change before we all have to deal with that kind of trench warfare during this championship. By all means, use this as a chance to mix things up, make us think on our feet and try new strategies. But at the very least, this should be changed for future events. With how things are going, we're about to see the exact strategies used last time, which will continue to be the fixed meta in any big experience event until there are real changes.