Mana Sensitive

Mana Sensitive (-10%) is a limitation for advantage origins. For the ability see Sensing Mana

Breakdown

Powers explains the breakdown:

• Mana: Low mana incurs -5 skill penalty (-5%)
• Anti-powers thwart abilities (-5%): Mana Damper; Magic Resistance (both advantage and spell, spells that dispel or protect against magic affects work on abilities exactly as if they were spells.

FAQ

http://www.sjgames.com/gurps/faq/FAQ4-4.html#SS4.1.12

In certain situations, like when determining what can go through a Force Dome, it's important to define exactly what a "magical" creature is. Although there is no single trait that defines it, it's easy to compose a short list of "markers":

• Any being that possesses a racial trait that has the Mana Sensitive limitation (p. B34), regardless of what that trait is. This does not include Magery, as is it a particular Talent and not a mana-sensitive trait.

powers

P27 says Magical at -10% is equivalent to this.

P176:

To keep magical abilities in line with spells – which have a FP cost to maintain and take -1 per spell “on” – the GM should probably enforce Abilities and Exertion (p. 159) and Multiple Feats (p. 158).

P177 explains the cost breakdown

The Magical limitation (p. 27) is worth -10% because magical abilities work at -5 in areas of low mana (and not at all if there’s no mana), allow targets with Magic Resistance a bonus to resist, and are subject to disruptive spells – Blocking spells can ward off attacks, Dispel Magic can end ongoing effects, and spells that resist magic can block new effects.

P178 under FP Cost and Source mentions a HUGE advantage which doesn't seem to be valued as an enhancement for powers

since FP spent on magic spells recharge in one second in areas with very high mana (see Mana, p. B235), so do FP spent on magical powers

P187 re Mana Enhancer:

GMs may rule that the Magical power modifier (p. 27) is only worth -5% if combined with this advantage.

fantasy

Mana-Sensitive with a hyphen instead of space, GURPS Fantasy mentions on pages 30 where it refers to p.133, while page 49 uses it on an Affliction (advantage). Nothing appears on 133 so this may be a typo.

errata

http://www.sjgames.com/errata/gurps/4e/fantasy.html also uses hyphen.

update

http://www.sjgames.com/gurps/resources/4eupdate.pdf mentions on 9 for making Knacks.

DF

GURPS Dungeon Fantasy 11 mentions on 6/37/38/40 and so on.

https://pseudoboo.blogspot.ca/2016/02/mechanics-sorcery.html mentions sorcery -15% is the -10% mana-sensitive combined with -5 Costs Fatigue

The -5 to die rolls for Low Mana is effectively not a penalty at all for advantages which do not involve rolls, it might be balancing for GMs not to allow this on things which lack rolls, and add some sort of roll to be penalized.

See also

• Mana Dependency
• http://forums.sjgames.com/showthread.php?t=122752