I'm back on track and needing help

[rybray]

Well for the 'smoke' you can add a particle system to the timer, when you feel it is appropriate (probably when you hear/see the explosion.) Multiple colored dusts or fogs, look through the available particle systems.

As for the sizzling and boom noise, I know for a fact there is a folder in the sounds menu called 'explosion' that has a sound of a rock exploding. It is all a matter of looking through the available sound files, and pressing the play button next to them to hear what sounds best.

For the damage, use the void GivePlayerDamage function on the wiki page and specify the player to be damaged for x amount of points.