Oppertunity attack, Lance, Warcaster, booming blade.

[Palfatreos]

So i was carfting around with a dark knight on a horse with lance/shield.

1)trigger for the opperunity attack use unarmed attack with 5 feet reach
2)war caster replace oppertunity attack with BB spell
3)BB use lance at 5 feet for the melee attack (with disadvantage)

Is this allowed or did i made mistake somwhere in the 3 reasoning? o.O

[stoutstien]

Disadvantage on attacks with Lance at 5 feet.
And strangely enough if you want to use BB with a Lance you need spell sniper to increase range to 10 feet

[Palfatreos]

ah forgot lance has disadvantage on close range.
However BB seem to work aslong that attack 5 feet away with any weapon if i read https://www.sageadvice.eu/2016/01/14/can-booming-blade-and-green-flame-blade-used-with-a-whip/ correctly.

[Keravath]

Just to clarify the other response.

You only get an opportunity attack when the target leaves your reach. NOT when it moves within your reach. The reach of a lance is 10'. So you do not get an opportunity attack when the target moves from adjacent to 2 squares away. You only get an opportunity attack when it moves out of your reach.

Warcaster allows you to cast a spell instead of using a weapon attack when a target provokes an opportunity attack. If you are armed with a lance then this happens at a 10' range. However, Booming blade only has a 5' range so you can not use booming blade with on an opportunity attack with a lance at all unless you also have the spell sniper feat. The spell sniper feat allows you to double the range of any spell that requires an attack roll. Since booming blade does require an attack roll to be made as part of the spell, with spell sniper you can double this range to 10'.

So ...
- opportunity attack with lance only allowed when target leaves your 10' reach
- warcaster allows you to cast a spell instead on op attack but that spell needs to have at least a 10' range
- you can use booming blade if you have the spell sniper feat that extends its range to 10'

Under no circumstances can you take an op attack with a lance when the target moves within but not out of your reach.

[Keravath]

ah forgot lance has disadvantage on close range.
However BB seem to work aslong that attack 5 feet away with any weapon if i read https://www.sageadvice.eu/2016/01/14/can-booming-blade-and-green-flame-blade-used-with-a-whip/ correctly.

Yes. But you can't take an opportunity attack with a lance or a whip at a 5' range. You can of course make a regular attack (which for a lance is at disadvantage).

[Palfatreos]

are oppertunity attack only allowed with weapons and not unarmed attack?

1)trigger for the opperunity attack use unarmed attack with 5 feet reach
2)war caster replace oppertunity attack with BB spell
3)BB use lance at 5 feet for the melee attack (with disadvantage)

basicly looking for either 1 of the 3 is wrong to pull of the combo. in this case you would say 1 never happens/ isnt valid?

[Lalliman]

It could be argued that, because you can always make unarmed strikes even while armed, someone who moves from five feet away to ten feet away would provoke an unarmed opportunity attack even if you're wielding a reach weapon. So yes, step 1 makes sense, though it is a loop hole and you should ask the DM whether he's ok with it.

The problem is step 3. If your opponent provokes an opportunity attack specifically from your unarmed strike, then obviously you can't use Booming Blade with a lance instead. There's no rule that says this, it's just common sense. You can't use Booming Blade with a lance as your opportunity attack if the circumstances don't permit an opportunity attack with a lance in the first place.