Can Green-Flame Blade take advantage of the whip's Reach property?

Question

The spell "Green-Flame Blade" is listed as a cantrip, presumably for the Bladesinger Arcane tradition and has a range of 5ft. In addition, the components for the spell are V, M (weapon) The spell reads:

As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell's range, otherwise the spell fails.

If using a whip (Finesse, Reach) , as part of the Snake style of the Bladesinger, can this spell be cast if the target is 10 feet away from the Wizard?

Meaning, does the target of the spell have to be within 5 feet of the weapon used to make the melee attack, or does it need to be within 5 feet of the caster?

Answer 1

It is possible by taking a feat

As Dungarth explains, the range of the spell limits the caster to use the weapon attack on a creature within range of the spell.

The range of Green Flame Blade is 5 ft, and requires the caster to make an attack roll with your weapon, so even though the range of your weapon is 10 ft, the spell's restriction still applies. BUT, read the first bullet of the Spell Sniper feat:

When you cast a spell that requires you to make an attack roll, the spell's range is doubled.

That means that, if you take the Spell Sniper feat, a target is in fact in range at up to 10 ft, meaning that you can utilize any reach weapon with the spell. However, the secondary target of the spell must still be within 5 ft of the original target, as the restriction is not based on the range of the spell.

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Update: Jeremy Crawford has confirmed on twitter that it works: https://twitter.com/JeremyECrawford/status/663511408269627392

Answer 2

No.

The spell's description states very clearly that the target of the attack must be inside the spell's range, which is always calculated starting from the caster. Range, the maximum distance at which a spell can be cast, is not to be confused with the notion of point of origin, which is used when dealing with AoE spells. While the effects of an AoE spell can extend beyond its range, the point of origin must always remain inside it. In this case, the original target would have to be within 5 feet of the caster, making it impossible to take advantage of the reach property of a whip.

In theory, you could still use this cantrip with a whip, but only as long as the target was within 5 feet of you. This seems to be concordant with Jeremy Crawford's interpretation, as can be seen in this Sage Advice answer to a very similar question.

Answer 3

In my opinion the spell is cast on a melee weapon that you are holding not on an enemy. So if you have a bugbear wielding a halberd that has the ability to cast it have fun burning your foes 15 ft away.