Arcane Bulwark

You inscribe a sigil onto six creatures of your choice using the material component of the spell.

Thereafter, whenever you cast this spell, choose upto six creatures of your choice bearing the sigil. These creatures must be visible to you and within range of this spell. You conjure a floating, intangible, spectral guardian or a similar entity, in an unoccupied space of your choice that you can see. The entity lasts for the duration, until you cast this spell again, or until it hits zero hitpoints. It cannot be the direct target of any attack, spell, or other magical effect and cannot interact with the world around it. 

The entity has 50 hitpoints. Whenever a creature with a sigil is within 15ft of the guardian and is the target of any attack, spell, or magical effect, it can use its reaction to trigger the sigil and reduce the damage they would have taken by half. The remaining half is absorbed by the guardian, which is reduced from the total hitpoints of the guardian.

In case of spells or magical effects that take place over an area or affect multiple creatures, if more than one person bearing the sigil uses their reaction to reduce the damage they would have taken, they can decide the order in which the spell affects them. The entity absorbs half the damage the creature would have taken, after they make the necessary save of that spell. The entity can only absorb damage from attacks, spells, or any other similar effects. Any additional effects from the source affect the intended target normally. On your turn you can mentally command the entity to move upto 30 feet.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the entity's zone of protection increases by 5ft and maximum hitpoints increase by 10 for each spell level above 4th.