I haven’t played Valorant, but a quick search makes it looks like they’re just spawning a wall mesh that scales up on the Z axis to look like it’s rising out of the ground. The initial streak of fire on the floor is likely just a particle effect set to match the size and shape of the wall mesh. It’s all special effects really. As I said, I may be mistaken since I haven’t played the game, but that’s what it looks like to me. I didn’t notice it changing shape much when spawned.
You don’t need to be using a spline to accomplish this. Just create a mesh for your wall, create an actor blueprint for it; set it to scale on the Z axis from 0 - 1 on begin play using a timeline to control how quickly it scales up, and then spawn it using “Spawn actor from class” at the location of the hit result of a line trace on your player character’s weapon.
If that’s all going over your head, then I might suggest watching Matthew Palaje’s tutorials: https://www.youtube.com/c/MatthewPalaje/videos
He goes through re-creating various gameplay mechanics from Overwatch so there’s likely to be some good crossover here for you.
As far as the blaze wall specifically, I’m not sure he covers anything quite like it, but you’ll learn a lot from his tutorials and likely my solution would make more sense once you’ve done so. Assuming of course that it doesn’t now, which it may in fact 
Oh, also, don’t use Tick. Like ever. There’s almost no reason to (there’s some, but…) and it tanks your performance. You should look into Timers as these also will run your code at a frame rate agnostic speed, whereas Event Tick changes depending on your FPS.