I am building a fate core petty dabbler in the arcane, and I am trying to build an alchemy stunt relating to turning lead into gold (lore skill instead of resources) what do people think is a good limitation for such a skill?

How would you do a puzzle boss with this system, for example a giant opponent that can only be damaged from the inside which means getting yourself swallowed and doing a fantastic voyage to attack its heart.

Or an enemy that requires plot devices hidden around the city to destroy like the Canopic jars in the Mummy.

A synthesist is a person who shares his body with creatures of the never never to gain access to their amazing power. A synthesist and his partners are bound heavily by laws and contract of their partnership, all power comes with a price and synthesist either be indebted to his partners or his partners indebted to him.

Musts: A synthesist must be in the know and must be able to constant contact the supernatural world. A synthesis should agree with his gm the limits each partners and discuss what bind him to his partners in advance of play.

Options:
Modular Abilities

Important Skills: None

Minimum Refresh Cost: -3

Here is an examples of a partners that a synthesist could have.

Name: Amon of the Burning Sands
High Concept: Banished Jinni
Power Options: Toughness, Recovery (catch Ice), Strength, Speed, Channeling Fire, Sponsored Magic Jinni   
Contract: The synthensist and him will work together until there shared purpose it complete (defeating Amon brother). Amon will not wrest control of the synthensists body from him and the synthesist will not carry out actions that that degrades Amon honor.

Having read the argument over on the extreme complexity thread I noticed a problem with the current blocking rules especially when they relate to magic and non- magic barriers. This Problem was illustrated when Richard talked about get through a ward by shooting bigger guns at it. Given how the game mechanics works shooting a Ground to Air Missile at that ward would be as effective as hitting it with a pencil as long as the attack rolls were the same.  This seems a little odd because a ground to air missile should be harder to defend against than a pencil even if both are wielded by masters.

Also wards have a minor problem/ feature that in game they can deflect lower level attacks indefinitely and better wards could easily sideline armies. 

I was wondering how high the complexity people would give plot device rituals?

For example how much complexity would you need to do a higurashi by which I mean seal off a area of about 5 miles in a time bubble that repeats every time everyone inside it dies. I was estimating that would take about 400 complexity with an effective duration of until the end of time, +50 complexity over about 50 zones, and about 300 shifts to do the time repeat trick.     

How much Complexity would you need to set every officer in the Chinese army on fire assuming you had a uniform as a focus, again this seems about 30 for effect and then an hard to estimate amount to effect all the people wearing the same uniform probably about 20, so a 50 shift ritual.     

I am trying to build a power to go alongside Outsider Powered Magic to represent the warping of reality caused by drawing power from beyond reality. I was thinking something along the lines you have an opposed discipline roll vs the power of the outsider magic you used and the difference between the roll and the power is treated like fallout which caused random bad things to happen (was thinking along the lines of bubbles of corruption in Wheel of  Time series or Final Destination style randomness). Any one got any ideas?

I was thinking of allowing players to buy specialization in other abilities outside of evocation after they bought a -1 refresh mastery power, these bonuses would use the pyramid and points would be divided between the different trappings of each skill, these bonuses would not stack with stunts. Would this break or ruin the game?