Is this homebrew "Protective Aura" spell balanced?

Question

Inspired loosely by The Witcher's Quen Sign, I've created this abjuration spell that's designed to completely negate the damage from a single attack (or similar instantaneous instance of damage like a fall or spell), a whole body shield that dissipates after one use. While concentration is kinda redundant if the spell dissipates immediately after one instance of damage, it's there mostly to as a restraint for higher level casting.

Protective Aura

1st-level abjuration

Casting Time: 1 bonus action
Range: Self
Components: V, S
Duration: Concentration, up to 1 minute Class: Paladin, Ranger, Sorcerer, Wizard, Warlock

A magical aura envelopes the caster's body, protecting it from damage. While the spell is active, if the caster takes any damage from a single instance such as an attack, a fall, or a spell, the caster must make a Constitution saving throw to maintain concentration. On a success, the caster takes no damage; on a failure, the caster takes half damage. Either way, the spell ends.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the spell remains active for an additional instance of damage for each slot level above 1st, provided concentration is maintained and the duration hasn't expired.

If I need to be more specific about "Balanced":

• Does this spell's power match it's level or should it be higher?
• Could this spell be easily abused, if so how and what should be added to the discription to prevent such a thing?
• Is it redundant to reiterate concentration and duration at the end of the spell's description?
• And most importantly, Does the spells description make sense, or should the description be re-worded a bit?

Also, while not necessary, if you can think or a more clever name it would be much appreciated.

Answer 1

It's overpowered

As SeriousBri points out in his answer, this ability is pretty much busted for any kind of spell level, but as you've currently worded the spell, it's especially problematic for Wizards and high AC classes like Eldritch Knights and Paladins.

If you're already rocking 20+ AC, most things that will hit you are either crits, or a spell of some sort, which means you're looking at only getting damaged once per turn. This makes the spell rather insane for Eldritch Knights and Paladins, who can simply pop this spell and keep concentration on it until it blocks a crit or a spell, and then recast it if the fight isn't over yet. The fact that it is a bonus action makes this especially troublesome, because it's often not that hard to find time to cast a bonus action, the spell would be a lot less 'must have' if it required a regular action, it prevents stacking Dodge ontop of this spell, making you almost impossible to damage for a turn.

For Wizards, this spell will break the game somewhat at level 18. Most games will never get to that point, but a level 18 wizard can pick a first level spell and basically treat it as a cantrip, casting it whenever you like as long as you have it prepared. I can't think of a single first level spell that I'd take over the ability to block a damage source per turn for a bonus action.

That's not even taking upcasting into account. I've played an Eldritch Knight focused on tanking, and this spell would have basically replaced all the other spells I used.

You're essentially trying to make a less powerful version of Resilient Sphere, so perhaps looking into the restrictions that spell puts on you will make it more manageable. Also changing bonus action to normal action will greatly depower the spell, turning it into a less good-for-every-situation spell.

Answer 2

Overpowered at ANY level as written

This spell can block 9 meteor swarm spells if cast using a high level slot. Yes it costs concentration but since you are unable to take damage that is barely a cost outside of affecting your offensive output.

I can't even countenance that level of power. I do have suggestions on how to balance it, but none have been tested and I don't think hearing my theories is going to help, but as it stands this is significantly more powerful than the shield spell, and in fact stacks with the shield spell to make the caster very difficult to hurt.

Also consider multi-class: A warlock / paladin (who can either cast it as a warlock spell or pick it from a feat) can wear plate mail, carry a shield, only really take melee damage on a 20 and still be safe from spells for the rest of their life with this spell.

Answer 3

This spell is rather strong.

1. The damage from "1 instance" is often low (especially for weapon damage instances), but it can seriously scale. And on spells, it scales really fast.

2. D&D 5e by design has offence beating defence as a design principle -- this violates that. A level 1 spell out-powers almost any attack. When defence beats offence, you get slow games.

3. It is a bonus action. This means it wins in action economy as well; most sources of damage require an action to put out there.

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Protective Aura

1st-level abjuration

Casting Time: 1 action

Range: Self

Components: V, S

Duration: 1 minute (Concentration)

Class: Paladin, Ranger, Sorcerer, Wizard, Warlock

A magical aura envelopes the casters body, protecting it from damage. While this spell is active and take damage and you pass your concentration check to maintain the spell, the first 10 points of damage is negated. If you fail the concentration check, the first 5 points of damage is negated. In either case, the spell ends.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or Higher, the amount of damage negated on a successful concentration check is increased by 5 per level for every slot level above 1st.

If cast with a spell slot level of 3rd or higher, the spell lasts 10 minutes (Concentration).

This version is still pretty strong, as it burns a 1st level spell slot to "pre-heal" by 10 HP; on the other hand, it uses your concentration to do so.

Answer 4

The easiest way to balance it this skill be to give it a damage block range similar to a lvl 1 damage spell. But I think it's more interesting to have it able to block 1 damage or 100 depending on how well it is played.

Most spells have some kind of secondary effect. To make this spell more D&Dish, maybe it would be better to have it force the attacker to have disadvantage, or give the caster advantage on concentration checks, and have it block a lesser amount of damage instead (eg 2d8).

Does this spell's power match it's level or should it be higher?

It is a powerful skill, but situational. I think it's fine.

Could this spell be easily abused, if so how and what should be added to the description to prevent such a thing?

The way it is now it seems difficult to abuse. Any intelligent enemy will hit the caster with a weak attack first, so saving it for that Apocalypse spell is difficult since you must maintain concentration.

The main situation where this skill is overpowered is against enemies that have 1 single attack per turn that is powerful and single target. In this situation it is amazing. Even a low level caster could tank for multiple turns for just 1 spell slot per turn. Of course, the enemy could always change target, or have a minion trigger the shield, etc. I think so long as you are paying attention your mooks will have no problems.

I feel that it would be unlikely that the caster will block more than a normal attack or a stray AoE skill with this spell. Even though it's potential is huge, I don't think it will play out the way a caster wants.

Is it redundant to reiterate concentration and duration at the end of the spell's description?

Not only is it redundant, it is dangerous. Readers will assume this is a special case, and wonder what they missed.

And most importantly, Does the spells description make sense, or should the description be re-worded a bit?

I would reword it to:

A magical aura envelopes the caster, protecting them from damage. The aura has 1 charge. If the caster takes damage while the spell is active that damage is prevented, and the aura loses a charge. When the aura has no remaining charges, the spell ends.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or Higher, the spell aura has 1 additional charge for each slot level above 1st.

I think this better integrates the higher level bonuses.

EDIT: If you are worried about some dumb mook dropping a Meteor Swarm on a shielded player, then either don't do that, or modify the skill to trigger when becoming the target of the attack, instead of when taking damage.

A magical aura envelopes the caster, protecting them from damage. The aura has 1 charge. If the caster becomes the target of an attack while the spell is active that attack is prevented, and the aura loses a charge. When the aura has no remaining charges, the spell ends.

Now you don't have to worry about an AC 20 caster being tanky with this skill. Even the dumbest of dumb mooks can nullify a 9th level cast with a handful of two weapon fighting goblin minions. Personally I think if you are struggling with handling high AC characters, you should look into non-attack ways of dealing with them. For example, spells that require a save! Also remember that the tanky character probably has a party that isn't as tanky behind them!