Sponsor: Typically self-sponsored, but is occasionally granted by creator gods or gods of fertility and life.
Agenda: Your own, if self sponsored. If granted by a god or other entity, that entity's agenda. Typically, the influence of Deus Vitae will drive you to use your powers in some way linked to your worldview- one user might be constantly tempted to make everyone around her happy, while another, disgusted by his own appearance, might be compelled to twist other's features into grotesque, nightmarish things.

Hmmm, well I generally do not like self-sponsored magic as being tied to the agenda of your sponsors is one of the few drawbacks of Sponsored Magic. However, I think this could definitely work as long as both the player and GM are diciplined in enforcing it.

Evocation: You can manipulate blood, flesh, bone, and other vital fluids and systems. You can also manipulate psychic energy, allowing you to use Spirit magic, but with more finesse and skill than a spellcaster without this Power.
Thaumaturgy: You can create and manipulate biological systems and life-forms of nearly any degree of complexity, from an amoeba to an oak tree to a human. You can also manipulate psychic energy and minds, allowing you to use fantastically powerful and precise psychomancy.

I'd be careful on the creating life part. While I have little knowledge of Dresden lore when compared to others on this board, I am fairly certain that even mending a cut is supposed to be incredibly difficult, so the shifts required to create life from scratch would have to be humungous I would imagine, especially considering this is self-sponsored, no one to cover the knowledge end of things.

Evothaum: You can use any ritual that can be cast with Deus Vitae with Evocation's speed and methods.

This may be my personal bias, but I really dislike the "anything you can cast with this sponsored magic can be cast as evothaum" thing. Evothaum is supposed to represent something the sponsored magic is especially good at, so saying that it is especially good at everything just seems like kind of a cop-out to me. Evothaum is a way to further develop the story of your sponsored magic via mechanical means, so I think it should be utilized as much. At the very least I think the chooser should have to pick whether they wish to specialize in the Biomancy or Psycomancy side of things.

Extra Benefits: You may use your complexity and control bonuses from Deus Vitae in place of your power and control bonuses for evocation, so long as the spell incorporates some element of biomancy or psychomancy.

This translates into several points of free refresh and I would not allow this on even a -5 Sponsored Magic. The only reason Kemmlerian Necromancy allows this is because it requires both Evocation and Thaumaturgy, so the incredibly strong bonus is balanced by the 8 refresh up-front cost. The user would always be able to include biomancy or psycomancy in the spell effect anyway.

I do like the flavor of it overall.
[Edit]
Hmmm, this came off more critical than I wanted. If I did not specifically say I did not like something, than I liked it!

Well the general consensus seems to be encouraging of the idea, but I would just like to add that while being an emissary to two beings story wise is fine, I don't think that the power should be taken more than once. This may be obvious, but for the sake of clarity I thought it needed to be said.

what makes it better is how it can bypass immunities. Magic immune no problem  40 foot hole from no where . Need some iron to take down tiny no problem every nail in the are pulled from area and hurled into his large ass I thinkni like it best

Eh, if something is immune to magic I think it is just immune to magic. You can flavor it however you want, but it still boils down to you using magic to attack something that is by nature immune to such energies. Fire magic dissipates moments before impact, the flung nails seem to curve around them, and the hole appears all around them except for a peninsula they can walk on.

But remember, you can flavor a role however you want. Example:
At the table: Bob roles a +2 on the dice, giving his character Miles a 6 weapon: 5 attack. The GM rolls a -4, so the attack takes out the vampire.

In the story: The vampire dodged yet another one of Miles' spells. How freaking fast where these thing? "Come on Warden, is that really all you have? How you ever expect to win this war?" It ducked behind a bookcase and gave it a mighty shove, attempting to flatten Miles. Oh hell no, you might have a beef with me, but you leave the books out of this. "Schlag!" A gale erupted from Miles' outstretched hand, knocking the bookcase the other direction. The vampire, startled by the sudden surge of power, leapt out of the way. Now, vampires are extremely quick and agile, but even they cannot ignore all of the laws of physics, especially the one about objects in motion staying in motion. Miles aimed at the spot where the Vampire would land, gathered his will yet again, and roared "Bewegung!" The blast caught the vampire square in the chest, knocking him through one wall and halfway through another, which is saying a lot considering they were made of concrete reenforced with rebar. Miles walked up to the broken body of the vampire and looked into its wide, surprised eyes, and said "Like that" before decapitating it with another force of will.

This may be a bit extreme, but the point is that you can flavor your spell as multiple different spells no problem. The mechanics don't so much tell the story so much as they summarize it. You can boil down a  30 minute martial arts fight into one contest, one roll, if you really wanted to.

One thing I've wished for is a list of sample Echoes of the  Beast, since it can be so diverse. Like what bonus and extra trapping can be good for a cat shifter? A bear? etc. I know it's individual and up to the table to decide, but jumping off points are alway neat to have!

Wikipedia! Seriously, just skimming through the article of the animal in question is really helpful for me. you may even find something about your animal that you didn't know about.

I like that more, how about this?

SUPERNATURAL STEALTH [-2]
Description: You are supernaturally stealthy. Seriously, what did you expect?
Skills Affected: Stealth.
Effects:
Imperceptible. Your Stealth is never penalized due to movement, cover, or environmental conditions. You may hide just as effectively while running through a bright hallway as while lurking in a shadowy corner.
Hard To See, Hard To Hit. You may use Stealth to defend against physical attacks. When dodging this way you may add Athletics bonuses from Speed Powers to your Stealth skill. However, you may not use Stealth bonuses from Cloak of Shadows or other similar abilities.
Perfectly Consistent. When rolling stealth for hiding, skulking, or sneaking, you cannot roll below a -2(-1?).
Invisible Attacks [-1]. When you make a physical attack, your Stealth supplements any attack you make.
Superior Supernatural Stealth [-1]. When rolling stealth for hiding, skulking, or sneaking, you cannot roll below a 0(+1?).

I'm not a fan of the alertness modifier on Hard To See, but I don't think it is game breaking by any means. I liked your idea of limiting how bad a person could roll. Superior Supernatural Stealth could increase the floor boundary instead of adding a flat bonus. I also changed Invisible attacks. Before someone could have Stealth and Fists at 5, and their opponents would almost always suffer a -1 to defend, essentially resulting in Fist attacks starting at 6. Having Stealth supplement attacks encourages people to have Fist and/or Weapons start at 4 or lower. This is minor but I think Stealth Powers should affect combat more indirectly than Strength/Speed/Toughness powers. Thoughts?

I added that trapping because without it, it seems like you're eventually gonna roll -4 and get found out if you try stalking someone long-term.

Isn't that the point of rolling though? I think being able to just use your stealth skill without rolling is a bit boring. Flubbing rolls is how things get interesting.

Hard To See, Hard To Hit. You may use Stealth to defend against physical attacks. When dodging this way you may add Athletics bonuses from Speed Powers to your Stealth skill. However, you may not use Stealth bonuses from Cloak of Shadows or other similar abilities. Alertness modifies the relevant skills of characters who attack you while you are defending this way.

I think this is where most of the balancing of the skill will take place. I'm not fond of the Alertness modifier. Decreasing the attacker's roll by one adds too much defensive power to a stealth power. Increasing the attacker's roll just doesn't make sense to me. If they are alert enough to not be fooled by your Supernatural Stealth, than their attack should be regularly effective, not more effective. Also, after a quick scan of OW, the only generic enemies that have an Alertness equal to or higher than their main attacking skill are Malks, Temple Dogs, Werewolves, and Lycanthropes. This modifier will be decreasing the incoming attack much, much more than it will be increasing or doing nothing to the incoming attack. Instead, I would suggest allowing the user to use this power against all targeted attacks (i.e non spray or zone attacks). I think it would be just as hard to hit Predator with a sword as it would be to shoot him with a fireball. What do you think?

Other than that I think the power is at the very least balanced-ish, opens the door for sneaky scions or Emissary's who don't want to take Channeling: Spirit of Glamours.

Look Melendwyr, you proposed a potential houserule (house-rule? house rule?), multiple experienced players have agreed that it is not a good idea, explained why, and offered alternatives using existing in-game mechanics that result on the same effect, but do not add more power to an already powerful class of player characters. You can take their advice, or ignore it and use the house rule in your games anyway (as long as the other players in your game agree to it). You don't need anyone's blessing as long as your group agrees to it, but I would take heed of universally given advice as it is usually universally given for a reason. There is no need for name calling or posturing.

Anyway I too agree that spellcasters do not need any buffs. Also, not everything that happens in the novels can be represented by game mechanics.