Expecto Patronum

[Severus]

Expecto Patronum (Part 2)/Patronus Charm Extension

We currently have an "Expecto Patronum" COMC spell that repels dementors. I do not believe for a second that this spell is used to its full potential. The idea of a patronus may have been poked at before but had never really come to a feasible or significant outcome enough for it to be created in to a "thing".

The first element of my 'Patronus Charm' idea is that it could act like a moving protego.
In spells such as Serpensortia and Dementia you are able to 'summon' snakes/dementors. The concept of that would work here; it's almost as though you would 'summon' your patronus.
Your patronus would then circle around your player icon, acting as a moving protego - it would 'endure' or 'reduce' damage based on your 'Defense' stat; this would provide an additional reason for players at Level 500 to invest in something other than just their HP/Damage stats. Whether the patronus moves directly one tile around you or in an area of 3 tiles around you (or other) is a decision that must be made.
Your Patronus would not die; instead, it is weakened until it is no longer in effect. I.e., it can only take x amount of damage for you (according to your defense stat) before vanishing; alternatively, it could be a 60 second thing.
It would be immune to your projectiles; i.e. Player A's Patronus would not be damaged or weakened by Player A's Glacius - however, Player A's Patronus could be damaged or weakened by Player B's Glacius.

How would you obtain the patronus?
This is up for debate. It could be taught as a part of the COMC Expecto Patronum or as a separate part for Charms.
Alternatively, it could be an automatic extension of the spell when a player hits a certain cap; for example, at 2000 Defense, your Expecto Patronum allows you to summon a patronus. On first use, a pop up would appear asking for you to confirm your permanent choice of patronus (see next question paragraph).
There may be other ways of obtaining it, such as if you have a certain K:D ratio.
Alternatively once more, it could be supplied as a reward from an Admin for a certain event.

So, what is the patronus?
This is another field completely open to debate. I imagine that there would be a list of default potential patronus you can choose from; for example, a deer, an owl, a phoenix, a wolf, an eagle, a troll, etc.
Alternatively, on achieving the ability to use patronus, your patronus is automatic according to your house; e.g. Snake Patronus for Slytherins. This could be then extended as reward or for hitting other caps.
Alternatively again, it could be an icon suited to your charisma. For example: a powerful feline for Justin such as a tiger ('meow'); a distinct wolf for Ash; an ape for me; etc. This would probably be a rarity.

What would be the spell attributes?
Probably would cause Expecto to use MP. Unsure how this would work; debate it.
A wand required.
Would it be available for use in safe zones? I'm unsure. It doesn't attack, it simply defends. However, would it make sense in safe zones? Again, this is up for debate.