Phase 1
Removing phase 1 would shorten trials and a lot of tedious busy work for each participant. Only a handful of people actually like phase 1.
Phase 2
No suggestions regarding challenger's battles since it didn't apply to me. However, forcing people to post decks immediately after their games would go a long way for everyone, especially since decks played could have been illegal. Same goes for master's tournament. Nilsieboy has yet to post any of his decks from this trials or last trials, which IMO means he shoudn't have received points from Phase 2. Also, many participants didnt post decks from losses since they already lost. I think there should be an additional loss of points if decks are not posted in a loss.
Regarding masters tourney rules, I really disliked the 100% upgrade environment. Combine that with a max of 33% off-element, it's even worse. Vast majority of tourney matches determined by coinflip or RNGfail. I suggest lowering the upgrades and allowing 50% off-element. Also, while at first I disliked the whole declaring elements thing, it ended up being an interesting twist requiring additional strategy.
Phase 3
I've never liked phase 3, but that's just me. Not really anything to suggest.
Phase 4
The ban system was interesting. They definitely made things more complex, but I didn't feel they were overly complicated. Not sure if there is anything in particular I would change regarding bans.