QUOTE (Tanegar @ Jun 7 2014, 11:11 PM)

It's my understanding that Astral Combat is used to attack astral beings.
Unarmed might be appropriate against a material spirit, but I chose simplicity on that score.
I also don't know what you mean by compatibility.
Breaking these up because i want to respond to all of these poitns
1+2) Is false in many occassions. Natural Weapons as well as Killing Hands flat out invalidate astral combat as a skill. An adept with it literally doesn't care about astral combat skills, since they get to use their full unarmed instead. (4a 196). Second, killing hands is already based around invalidating spirit defenses, which is also something spirit leash aims to do.
3) Attacks of will are also based around overcoming/overpowering spirit's natural defenses, and exerting your will over their being - its quite literally having the willpower to cut through their ITNW by sheer mental grit. Spirit leash is similarly themed, except goes one step further and messes with their cohesion and ability to interact with the physical plane. They have very similiar themes, and you should look at making their rules work together - perhaps a dice pool/dv bonus per adept power level, or allowing the attack to be made(perhaps with a skill other than Banishing, which adepts don't get unless mystic)
Because you mentioned simplicity - and spirit leash as current is anything but - Here's a game design exercise.
Spirit Leash - Element Ap Half - Whenever a spirit is damaged by an attack with this element, they must pass a Composure Test (unsoaked DV) or their possession/materialization power may not be used or canceled voluntarily until the start of the next Combat Turn, nor may they Astral Shortcut. Additionally, the adept may choose to disrupt a spirit's sustaining of either power.
This gives the adept a choice to lock a spirit into the physical, or kick them back to the astral, and is cleanly worded.
This gives it a base cost of 2 PP to use via elemental attack, and a 0.5pp tax to get killing hands as a prerequisite
Want a called shot nerf to make it harder to use? Change cost.
Want it to not do punch damage in addition? Change cost.
Drain included? Change cost.
Make it a Power instead of an Element, which would work on elemental spells? Change cost.
Make a thematic exception to work on astral entities? Change cost.
Ip/action stealing idea? Change cost.
Reducing the spirit's ability to resist? (2x force attibute tests are a spirit's strong point) Change cost.
Make it a cheap leveled adept ability, with successive levels giving a dice bonus? Change the cost.
Make it a dual-natured attack that can drag astral spirits to the physical, forcing them to manifest? Change the cost.
Rules hiccups to address:
Changing IP amounts: a spirit booted to the astral from physical gains an IP. Do they get it back immediately? Is this a foundation for the lose-an-action idea? What about losses if dragged to the physical.
Manifested quasi-real spirits: spirits are explicitly able to Manifest(like a projecting mage) as well as Materialize, which typically gives them immunity to being attacked if they just want to talk. How does spirit leash work against a spirit in this state? How does it interact with a manifesting Magician?
Percieving adept vs Astral Spirit, using killing hands or a weapon foci? What happens?
Your goal now is to A) Properly balance it and B) word it concisely. Good luck!