Booming blade for sorcerers

[Brother carc]

I think I've stumbled across a fun combo for my current game but I'm a total newbie with 5e so I want to check I haven't missed anything.

I'm playing a drow draconic sorcerer with a rapier and the mobile feat.

If I ever find myself in combat (or get a good opportunity to jump into combat) I cast booming blade, twinned if there's more than one opponent, then I can step away from combat with no opportunity attack and leave the DM to decide if he wants to come after me and take the 'boom'.

I'm at level 12 now so this is a potential 2*(3d8 +3 + 3d8)

Not bad for one cantrip and a sorcery point...

I can also quicken a different spell if I have the sorcery points to spare.

Is there anything I'm missing though? Could I make this combo even better? Is it entirely legal?

[Easy_Lee]

It's legal. If you want to do more damage, you could multiclass two levels into paladin and smite at the same time. Note that this triggers when you hit with a weapon, not when you make an attack. Thus you can use it with the blade cantrips, but it won't twin.

Edit: and if UA is allowed, strongly consider hexblade. Even one level of hexblade warlock gives you medium armor, shields, a bonus action curse that can heal you, and lets you use charisma for your attack and damage rolls with proficient one handed weapons. In other words, one level of hexblade will turn you into an effective SAD gish.

[Koren]

I'm not so sure Booming Blade can be Twinned but even if not it sounds like a Melee Sorcerer could be awesome

[Easy_Lee]

I'm not so sure Booming Blade can be Twinned but even if not it sounds like a Melee Sorcerer could be awesome

It seems to work given that booming blade only has one target. People get into debates about green flame blade, but I've never seen an argument against BB.

[Zman]

Yep, used this combo quite well with a Fighter/Sorcerer I was playing. I didn't use mobile, but used Haste instead for the disengage haste action and the ability to literally fly around the battlefield. With a touch of fighter I had the ability to action surge as well to double up the twinned booming blade and could quicken another if I needed it. Once, I got like four of five booming blade connections and just stood back and watched, it was delicious.

[Brother carc]

Sadly don't have the strength to multi class into paladin but I had a look at hexblade and it looks perfect for my needs.

Just need to run it past my DM and hope he's ok with UA