Does Teleport activate booming blade?

No, teleportation doesn’t trigger the secondary damage.

Can booming blade be thrown?

Booming Blade definitely works with the feat. Can you cast Green Flame Blade on a melee weapon that can be thrown? Yes, but GFB must be a melee attack and has only a range of 5 feet. So you can attack with a spear as part of casting the spell, you just can’t throw the spear as part of casting the spell.

Does sneak attack stack with booming blade?

Yes they do stack. It’s worth noting though that booming blade only adds 1d8 at 5th level, unless the creature hit moves. And it’s not really imbalanced (even if it is a little more outright damage). You had to give something up to get that booming blade.

Can green flame blade hit the same target?

You don’t have to target another creature, per rules intent As quoted in the question, green-flame blade has you make a melee attack with a weapon as part of the cantrip; on a hit, green fire also leaps to another target of your choice within 5 feet.

Does green flame blade hit the first target?

Does Green-Flame Blade deal its magical damage to the first target you hit or just the second? At level 1 GFB deals 0 fire damage to the target of your attack and your spellcasting ability modifier in fire damage to the second target. So you don’t deal any magical damage to the first target until level 5.

Why is green flame blade good?

Green Flame Blade (GFB) is a damage cantrip that can hit multiple enemies. That on its own makes the spell a great addition for numerous classes. Any class that has a single attack will benefit from this cantrip. Also, the damage to the second target is not that great, even as the cantrip levels up with the character.

Can you twin green flame blade?

Green flame Blade can’t be twinned As clarified in the PHB errata: To be eligible, a spell must be incapable of targeting more than one creature at the spell’s current level. Green flame blade is able to target two creatures; the one you attack and one next two it.

Can you counterspell green flame blade?

Under the post-November 2020 rules text: No, the attack does not resolve as it is part of the spell’s effect, which Counterspell prevents. In November 2020, a Sword Coast Adventurer’s Guide Errata was released, changing the spell text in question significantly.

Does green flame blade work with Warcaster?

So as you said, green-flame blade is not compatible with warcaster OAs.