Disadvantageous Alternate Form

Disadvantageous Alternate Form (informally called Disadvantageous Form due to character restrictions in tagging) is a disadvantage version of the Alternate Form advantage. It was explained in the designer's notes for GURPS Powers by Sean Punch at http://www.sjgames.com/pyramid/sample.html?id=5782
: a disadvantage, worth -5, -10, -15, or -20 points for Rare, Occasional, Common, or Very Common trigger conditions, respectively.
:The point value of the form isn't important . . . unless the GM feels it is. Turning into something extremely vulnerable, like a clam, can be a problem. Becoming the Death God can be useful if you abuse it properly; just be sure you're on enemy territory when the trigger gets pulled.
:As such, the GM might wish to add a percentage of the point-value difference between the shapeshifter's base template and the shifted template to the above cost -- perhaps 5%, 10%, 15%, or 20% depending on rarity; perhaps more.
This is also mentioned no page 18 of GURPS Horror. Mentions to use same multipliers as B161's Weakness
Much cheaper to Afflict on someone than the advantage!
==other approaches==
GURPS Fantasy wrote a Wolf Form template and instead of DAF, treated someone who shapeshifted into it as having a Compulsion to use shapeshifting.
GURPS Powers talked about using Uncontrollable
H62 suggests using Unconscious Only + Uncontrollable limitation limitations (originally from P78) as one approach. It seems to ignore the errata's suggestion that it's unfair to price it as an advantage.
However there IS a distinction between these: a Will roll can mitigate the Uncontrollable trigger, as B116 explains. DAF can't do that, so it should be worse point-wise.
==explanations of pricing for higher-value forms==
This can be very confusing so listing both expanations beside each other could be helpful.
Errata:
:add a percentage of the point-value difference between the shapeshifter's base template and the shifted template to the above cost -- perhaps 5%, 10%, 15%, or 20% depending on rarity; perhaps more.
Horror:
:read disadvantage value as a positive percentage (so 5%, 10%, 20%, or 30%), and add that fraction of the point-value difference between your base and shifted templates, rounded up, as a positive cost.
No examples are given of either of these texts in action to guide people who don't understand their readings.
==Shadow Form dilemma==
While this was one of the original examples, this was because it was an "Always On" ability, not because it made you an NPC while turned.
The idea of this being a disadvantage should probably be rexamined. After all one major component is operating like Insubstantial (B62) with Always On -50% and Illusory Form (F128) -15% and No Vertical Move -10% (F129) and Noisy -5% (P56). Applying -80% to 80 is still advantageous: 16 points!
B83's distinctive drawbacks compared to the above-limited Insubstantiality
*not truly insubstantial: need shoulder-width cracks to slip through doors
*two-dimensional: it's difficult to interact with others:
*"cannot perform any purely physical attacks" (insubstantial foes can attack each other, or get 'affects substantial' on their ST-based damage)
For comparison, No Physical Attack is a -50% limitation on Extra Arms, so having it on your base 2 arms is worth -10: half the value of Shadow Form -20. "Cannot Kick" is worth -5.
Category:Disadvantages