“Prevent powers on this street.”
What it does (for you in hands normally):
You’ve made a hand and you don’t want your opponents to screw things up for you by changing the board texture, looking ahead in time too much or changing their hole cards. So you use your (overpriced) EMP card and just ruin the fun for everyone.
This is great in theory – it’s like a “back to boring old Hold’em for a street” card. And people will rightfully assume you have a decent holding even if you’re doing the old EMP → All-In as a bluff maneuver when you’re desperate for chips.
In practice, why does this card exist as a 4 mana option PokerStars? For one – the only time you’re likely to use this as a bluff is when your stack is healthy enough to not need to make wild variance-riddled plays, and when you’re low stacked and use it – it doesn’t matter. Your opponents still have 2 cards. This is still poker.
Their calling ranges are wide open when you’re shoving your last 5 BBs so using EMP – other than killing action from your opponents bottom-of-calling-range hands, does nothing. They still call with most Ace and King highs. They call with lots of other stuff too. You’ve just wasted 4 – count ‘em FOUR – valuable mana for slight gain – when you could have gone all in and locked the board up from changing anyways.
This card does have value – specifically it has 1 mana worth of it.
Is it good?
No. Period. Adequate as a cheap 1 mana card protector but that’s about it. Note “adequate” in this case means something closer to “meh, I guess”, then “yay this is good”. This is a card that ruins your own action and is of no use at all if your opponent’s wake up with even a decent holding. If anything it’ll make them more emboldened as they know you can’t do some fancy PowerUp redraw to beat their hand.