While planning out the new Druid I'm rolling, I found many discussions on the internet saying that the War Caster feat is useful to take as it helps the druid maintain concentration while using Wild Shape (including at least one occurrence on this site.)
The War Caster feat (PHB 170) says:
Prerequisite: The ability to cast at least one spell
You have practiced casting spells in the midst of combat, learning techniques that grant you the following benefits:
- You have advantage on Constitution saving throws that you
make to maintain your concentration on a spell when you take damage.
(Other benefits omitted.)
However, the Feats section (PHB 165) says:
You must meet any prerequisite specified in a feat to take that feat.
If you ever lose a feat's prerequisite, you can't use that feat until
you regain the prerequisite. For example, the Grappler feat
requires you to have a Strength of 13 or higher. If your Strength is
reduced to below 13 somehow — perhaps by a withering curse — you
can't benefit from the Grappler feat until your Strength is restored.
When you use Wild Shape, a couple of the many rules (PHB 67) say:
You can't cast spells, and your ability to speak or take any
action that requires hands is limited to the capabilities of your
beast form. Transforming doesn't break your concentration on a spell
you've already cast, however, or prevent you from taking actions
that are part of a spell, such as call lightning, that you've
already cast.You retain the benefit of any other features from your class, race, or
other source and can use them if the new form is physically capable of
doing so. …
(Other rules omitted.)
So, it appears the logic goes like this:
- Cast any spell that requires concentration
- Use Wild Shape and continue concentrating on the spell
- Druid no longer has the ability to cast spells (unless they are level 18+), but retains the benefit of all feats that the new form is capable of using (as a feat is a feature of the class or race – ASI or human variant)
- War Caster feat can no longer be used as the prerequisite is no longer met since the Druid doesn't have the ability to cast at least one spell anymore
- Any Constitution saving throws made to maintain concentration on a spell while taking damage will NOT be at advantage (assuming no other source of advantage is present)
Is my logic correct for a druid from 2nd to 17th level? Or is there some other rule or ruling that keeps the advantage for the Wild Shaped War Caster Druid when making these Constitution saving throws?
(Druids get Wild Shape at 2nd level; at 18th level, druids get the Beast Spells feature, which lets them cast spells that don't have material components while in Wild Shape. Thus, the question's only relevant at levels 2-17.)
Given the internet's love of pointing out when people are wrong, and me finding at least 3 instances where someone explicitly mentions War Caster as being useful while using Wild Shape, I'm inclined to think I've missed something. However, I can't find what I've overlooked in the rules. (Although, based on past experience, about 7 second after posting I'm sure I'll figure it out.)
Best Answer
Being prevented from casting spells isn't the same as losing the ability
To start with having the "ability to cast one spell" from a feature and not a magic item is the same as "being a spellcaster" as defined in the DMG (p. 135; clarified in Errata), so we can use those terms interchangeably.
The core of your question is whether having an effect saying "you can't cast spell" means you lose the ability to cast spells and therefore you no longer meet the prerequisites of War Caster. This isn't covered very well by the rules (shockingly), but we can look at some similar cases.
Lets say all the spells of a spellcaster have a verbal component (as is very likely). They are standing in the effect of a silence spell. They now have no spells they can cast, but they categorically still have the Spellcasting feature it's just not doing too much for them.
In a less likely scenario, say all the spells of a spellcaster have a casting time of one reaction. When the criteria for these reactions aren't met, they have no spells they can cast and so can't cast spells. However they still have an ability to cast spells.
A very similar argument goes for a Paladin or Ranger (no Cantrips) who uses their last spell slot. They would not be able to cast any more spells, but they still have an feature which grants them the ability to cast spells.
Having the spellcaster count as "losing the ability to cast spells" would make them no longer be a spellcaster, and therefore no longer be attuned to any magical items which "requires attunement by a spellcaster". Losing attunement to your cool magical staff (or similar) because some cast silence on you or you used your last spell slot, is unfun, weird, and to a lot of players, dumb.
If a ruling making the game less fun isn't enough, also note that you would have to do a lot of on/off tracking on whether a creature counts as a spellcaster at any point of time, both for that feat (and others) as well as magical items. This adds complexity to the arguably most complex part of the game.
So does a Druid lose the "ability to cast spells and thus the benefits of War Caster? This would then hinge on them keeping their Spellcasting feature, which they should. Otherwise, 18th-level feature Beast Spells wouldn't do much, or would need to let them keep the feature without saying so in its text. And as a general principle features (and spells) only do what their description says.
We are now allowing the Wild Shaped Druid to have a Spellcasting feature without having the ability to use that feature (i.e. cast spells). This is consistent with the part of Wild Shape which determines retention of features:
If we read it as two separate sentences:
which isn't unreasonable.