Modern: Easily the most popular format among competitive players, Modern allows you to use cards from Mirrodin onward, save for Commander deck cards
As you can see Storm, is more than just a combo finish, it can be swarming the board with tokens, casting a lot of artifacts or spells from exile to have a spectacular finish, or playing all your cards over and over to eventually close out the game
It is amazing for damage output, and is reminiscent of the emblem shenanigans of Magic 2020 's Chandra, Awakened Inferno
Act on Impulse relies on you having plenty of mana available
If you target an uncounterable spell like Abrupt Decay with a Counterspell, the counter simply fizzles and does nothing, similar to when you target an indestructible permanent with something that says destroy. You technically can do it, but it has no effect other than ticking up your storm count