Mods can now have cards do pretty much anything, so I thought we could share ideas here. There has been a thread like this before, but I think it has more or less been a joke (remember order delay card delay card?). However, if anyone finds it back (I couldn't), please share the link here.
I'll start with an idea:
Russian roulette card Works like a reinforcement card of X armies 80% of times, but like a bomb card on your own territory with the largest stack 20% of times.
(Uno) reverse card The next card your opponent plays will have the opposite effect. A reinforcement card will instead deduct X armies, an order delay card will play as an order priority card, a blockade card will do... something!
Paratrooper card A random territory of your opponent beyond the front line (not one you already border) becomes yours. If there are any movable armies on it, they are eliminated. If you border all your opponent's territories, the paratrooper will land on one of the border territories, but only then.
Place a random mine field on a territory you control. If your opponent attacks certain territory, the mine field goes off, removing the mine from the territory and reducing your opponent’s stack by 50%. This is good when your opponent is attacking a single territory and you know which one but sucks when there are multiple territories and you probably won’t know which territory to use the card for.
Wild card A random change of settings occurs. This can be be anything from the attacking kill rate suddenly increasing to 75% over an airlift card suddenly being given out every turn to South America suddenly being worth 6 armies per turn.
No sense of direction card For the following turn, wherever your opponent transfers armies, they will instead head to any random other territory they border.
stefano36000 card Can only be used in games with at least three players. You pick which other player you play it on. That player will, at an unforeseen moment from next turn to in 36 turns, suddenly be eliminated without any warning or explanation. Nobody except you can see that the card was played.
Nuke card. After 100 games played (or for every 100 games), players receive a 'nuke card' they can use in a ffa game to automatically win...or to eliminate another player.
Tsar bomb card Can be played on any opponent's territory you border. The bombed territory loses 100% of its armies, all bordering territories lose 60% and all territories bordering these (two away) lose 20%. Hence, your own territories are bound to suffer too.
INSS card / Landria card / Normal card (Although it's kinda impossible for coding)
For some reason, the income system is switched to INSS or landria mode or normal mode when playing on an alternative income system for 1 turn. However, it's random on which system you end up on.
Airstrike card Like an airlift card, except that it kills a certain number or percentage of armies instead of transferring them. Can be played on fogged territories too, in which case you will not see the impact.
Zombie Apocalypse card. A card can be used to drop into a specific location of an opponent. That location turns into a 'zombie' haven and expands 5x on attached territories for every turn. Extra cool if there were actual little zombies on the territories walking around.
Alien invasion card Like an intervention card, except that it has preferred kill rates and/or starts with 1000 armies. The last player to survive the alien invasion wins.