D&D 5E How does Mage Slayer feat reaction attack sequence with the spell effects of the triggering caster?

[Mort]

Point of order- does Mage Slayer actually say it's an opportunity attack? My recollection is that it does not. It says you can make an attack as a reaction, but doesn't call it an opportunity attack.

Right, it says:

• When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature.

Not that the spell provokes an opportunity attack, it's similar in that it uses your reaction to make an attack - but it's not the same. For reference there are feats that do state exactly that. Polearm Master, for example:

• While you are wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter the reach you have with that weapon.

 

[Mort]

I'm definitely not. They have the terminology "opportunity attack" available and didn't use it.

I'd certainly consider house-ruling the feat to make it one, though.

It might matter. Say the mage slayer ALSO has warcaster. If the mage slayer attack was an opportunity attack, they could cast a spell instead of attack.

 

[SkidAce]

It might matter. Say the mage slayer ALSO has warcaster. If the mage slayer attack was an opportunity attack, they could cast a spell instead of attack.

Brilliant.

 

[Sorcerers Apprentice]

I've never actually seen anyone take the mage slayer feat, it's usable so rarely, and unspectacular even when it does trigger. And of course it's close to completely useless if the DM uses MoM monsters, since NPC spellcasters no longer cast spells but use various special abilities that look like spells but aren't

It could do with a serious buff. Something like "When a creature attempts to cast a spell within 5 feet of you you can use your reaction to interrupt the casting with a melee attack. If the attack hits the caster must make a concentration save, or the spell fails", would be worthy of a feat.

 

[Mort]

I've never actually seen anyone take the mage slayer feat, it's usable so rarely, and unspectacular even when it does trigger. And of course it's close to completely useless if the DM uses MoM monsters, since NPC spellcasters no longer cast spells but use various special abilities that look like spells but aren't

It could do with a serious buff. Something like "When a creature attempts to cast a spell within 5 feet of you you can use your reaction to interrupt the casting with a melee attack. If the attack hits the caster must make a concentration save, or the spell fails", would be worthy of a feat.

I'd be happy if it was reworded "spell or spell like ability..." making the condition quite broad and much more worth it.

 

[ECMO3]

I've never actually seen anyone take the mage slayer feat, it's usable so rarely, and unspectacular even when it does trigger. And of course it's close to completely useless if the DM uses MoM monsters, since NPC spellcasters no longer cast spells but use various special abilities that look like spells but aren't

It could do with a serious buff. Something like "When a creature attempts to cast a spell within 5 feet of you you can use your reaction to interrupt the casting with a melee attack. If the attack hits the caster must make a concentration save, or the spell fails", would be worthy of a feat.

I have only seen it once, early in 5E on a Monk-Sorcerer and I don't think it ever got used.

I have a 19th-level Shaddar-Kai 11th Fighter (Zhetilar's Finest)/8th Ranger (Fey Wanderer) and I am thinking about getting it at 20th level (Fighter 12). The character is primarily a melee character with a lot of frightened options.

The campaign is coming to a close and the big boss is Vecna, who presumably casts a lot of spells, so that is why I am considering it. The other option is an ASI to boost Wisdom to 20 or perhaps Great Weapon Master since she usually uses a magic flaming Maul.