War at it's core is a team based vault building pvp event. Then we added extra stuff to it.
I really, really don't like when we mess with the vault later on with event cards or whatever. The hard choices shouldn't be which cards to discard, or left up to RNG. The strategy is in building the vault to begin with, and then making the hard choices on how to play with it.
Event cards are by and large bad. I have seen a handful that were balanced for each and every team, but more often than not they aren't. Not to knock people making the event cards, it's just really difficult to make good ones. I would get rid of these in a flash.
If you want more variation in War I would suggest bans like we've used successfully in other events. RR had some interesting ideas for Trial bans that added strategy and variation to the matches. An idea could be like at the start of War every element gets to pick a franchise card of theirs that they and only they may use. So like Entropy might pick Nova, and then they are the only team that can use Nova.
Propaganda is fun but it's always rushed. I would let propaganda run on till about Round 6 and then give the bonus, and make the bonus like 12 individual cards for first place, 11 for second, 10 for third etc AND I would make this the only opportunity to add cards to your vault outside of building it.
So while I like vault building I actually dislike the whole discarding and whittling down mechanic we use to eliminate players. I would massively change War by giving every player 60 cards and 3 lives. When you've lost 3 matches you're out, and you take the 60 cards you brought to the vault with you. While you're still alive your 60 cards are shared with your team mates. Put in special rules where a player can sacrifice themselves to save the General if the General is about to run out of lives. Or that support team can work to adding an extra life for the soldiers if they are successful. IMO it would be simple and would make War a lot more War-like as opposed to spreadsheet management-like.
And lastly I personally do not like pvp'ing with upgrades. More upgrades ≠ more fun. I liked it back when only the General and Lt. had a handful of upgrades because it was meaningful, but maybe that's just me.