Transcendent Pneumatic Alleviator

What's it called? Transcendent Pneumatic Alleviator (in brief, TPA)

What does it do? This spell is such a staple fare for wizards it is almost needless to explain what it does. Nevertheless (just in case some newbie reader is around), TPA is your main magic protection spell, after the floating shield. The big brother (and more effective version) of Sorklin's Field of Protection, it will create a protective shield around you which will suck up hits until destroyed.
Four things of importance about it:
1) The number of hits it receives will make it change colour (giving you a clue of how much longer it is going to last). It starts with invisible, then dull red, bright red, wobbling orange anf flickering yellow. Once in the last stage it is almost broken, and some damage may pass through it even before it 'breaks'.
2) Even after it has been hit, if the damage stops, it will recover over time (say, a wobbling orange will go back to bright red, and so on). Nevetheless, a recovered shield will be weaker than before. Also, time acts against the shield: after a certain amount of it, the shield will break even without any damage.
3) The magic shield is meant to work as a 'backup' to the floating shield (EFF), allowing you offensive casts and some hits to pass the floater without disturbance. Once a floater is down, it will buy you pretty little time (depends against whom and how many you're fighting) to run away before breaking, so keep an eye on the 'breaking' message (There is a sudden white flash. Your magical shield has broken). It is a good idea to turn the line into a colour trigger, for easy glance in combat.
4) It can be cast on yourself and on others (in fact, it works great for others, dodge or parry/armour users, as they will get few hits using their defences, unlike wizards, and the few they get will be negated by TPA)

Where is it? As the idea behind it is making a shield out of almost thin air, it belongs inside the Invoakatyons in thee Mysterie of Wynd grimoire, at the Unseen University Library.

What does it require? A handful of ash and a shield, of some kind. The ash is consumed in the process. The shield has to be a 'real' one (i.e., one that you can 'hold') or the efficiency of the cast will be very low. It is good idea to get your hands on the lightest available (right now, medium leather).

What skills do I need? Evoking, Air, Chanting, Enchanting, Channeling

Has it worked? The proper output should read something like this:

You prepare to cast Transcendent Pneumatic Alleviator on xxx
You consider the function of a shield.
You send your thoughts probing into the air around xxx.
You recite a rumbling roll of rustling rhymes.
You lif the ash and scatter it around xxx.
You weave a magical impact shield around xxx.
With a noise that sounds like “Plink!”, everything around xxx flashes red for a moment.

Help Information:

Transcendent Pneumatic Alleviator - Magical Impact Shield.

The Transcendent Pneumatic Alleviator is a first order defensive spell which places a magical impact shield around the target.