I realise this would be a lot of explaining… …
How would I make a TNT blueprint? So if your too close when it blows you die. 
This is actually a lot of explaining and is mostly basics that you should look up in YT videos etc… There is a lot of content regarding things like explosions.
Basically you’d have an actor that has a collider (for example a box collision). In the overlap event of this collider you’d cast the overlapping actor to the Player Pawn and if the cast works. You trigger an explosion (see YT on this) that applies damage and force, triggers a particle system (see Niagara tutorials on this) and finally destroys itself (the TNT actor).
Hope this was a bit helpful!
Your a legend.