What a Twist!

I've been working on a project for a while now, and I have had a thought that might make it more interesting and cinematic.

Here's where the thought came from: I hate the Adventure Deck. Hate it, hate it, hate it. It's ridiculous, game-breaking, and often runs my story off the rails. However, I do like the idea behind it, of mixing the game up and giving the players some more control.

So I thought, why not give it to the GM?

And then I thought, why not let the players choose when it gets used?

So I'm toying with the idea of a Twist Deck. The Twist Deck is a deck of cards the GM has which can be used by the players for risks and rewards. Currently, the idea is if a player spends a benny and the reroll succeeds with a raise, the player can keep the benny if she draws from the Twist Deck. The Deck would be different based on the game you're playing, but here's an example for Swarm on the Somme, a World War One-meets-Aliens campaign I've been working on with my brother.

Achtung!: A squad of German soldiers equal in force to the player characters plus allies shows up on the battlefield. Roll to determine their reaction.
How Could This Get Worse: An NPC ally is infected with alien larvae, which will later burst out of the poor sod at the worst possible time.
Fire!: A fire breaks out on the battlefield! It starts as 1d6 Small Burst Templates placed randomly. Check to see if they spread each round.
Gas! Gas!: Chlorine or mustard gas drifts onto the battlefield. It's a Medium Burst template that moves 1d8" randomly at the top of the round.
They Just Keep Coming!: A band of eight Drones, led by a Soldier, pour onto the field.
Heavy Rain: A rainstorm starts, reducing visibility to 6" for humans and 3" for most Bugs. Flying drones are grounded and gas is useless.
Stash: What luck! A cache of 1d10 potato mashers (German trenches), Mills bombs (British trenches), or rifle grenades (French trenches) is somewhere on the field.
Take It To The Maxim: A single Maxim gun is somewhere on the field. It is fully loaded and ready to fire.
Bad Luck: The GM gains a benny!
Tougher Than It Looks: One of the Swarm is promoted to a Wild Card instantly.
Out of Ammo: Damn this rationing! All allied Extras have their Ammunition reduced by one level.

There would be probably 3 of each of the "bad" cards and 2 of each "good" card, but you get the idea - plenty of options for making the battle more interesting and upping the stakes.