I have built a 5th Level Rogue Swashbuckler who took Magic Initiate feat at Level 4 to do some extra damage with Booming Blade and Green Flame Blade.
When using a normal rapier with Booming Blade at current level on a Sneak Attack he deals: 1d8 weapon damage + Dex mod + 1d8 thunder damage and 3d6 Sneak Attack.
Do all of the dice double on a Critical Hit/"Nat 20"?
Would the total roll then be: 2d8 weapon damage + Dex mod + 2d8 thunder damage + 6d6 Sneak attack damage?
So would this be an instance that a weapon attack, a spell, and ability crits?