Why not:

Pheromones now upgrade those checks instead of boost.

But...

After each check using a Pheromone bonus the player must make a Resilience check. He suffers strain = Threat, and failure of the check reduces his Strain Threshold by 1 (cumulative) until he is cured. If you want to drop a Dpoint on him you can have a Despair on this check generate a crit.

So the player won't be completely hamstrung, and can use this new power, but he runs a risk each time he does.

Don't make it tied to Destiny dice. Make it cost Strain to use.

Lowering the max ST every time is...pretty intense, especially if there's no cure, or the cure is a campaign unto itself.

Id say it would be fairly balanced by allowing him to use it on all creatures, get 2 boosts, but also a setback die to all of his rolls to use it. Maybe make it two setback dice or only only one boost when using it on animals.

I think ghostofman is onto something there, and would use that as-is if you really want to make things desperate.

Alternatively, you could utilize a Force Die. Either give an extra boost die and if the Force Die comes up as Dark Side, that number of Strain is taken, OR give the standard Boost Die with a Force Die, and any Light Side Pips count as successes/advantages (your call) while the Dark Side deal both Strain AND Wounds.

The ability upgrades his dice pool once for each point of strain he chooses to spend up to a maximum of his Presence. So, if his Presence is 3, he could upgrade his dice pool 3 times and suffer 3 strain. This is very, very powerful.

The catch is that his strain does not recover as quickly it should. It takes him a full week to recover a single point of strain.

Or, if you want to make it nastier, he suffers wounds instead of strain.

Or critical injuries.

I'm guessing you're using the Species Menagerie, but I can't find a version of it that matches what you're describing. With the rules that you're using, is it normally treated as a power/action or is it just an inherent trait that always applies?

With the agent in effect, do you want it to be driven by player choice (again, power/action/etc.) or do you want it to be inherent? That could have a big effect of how you implement the downside.

If it's player driven, I think the suggestions above should give you a good selection of ideas. If it's meant to be automatic, changing the effect would probably be the best way to go. For instance, you could make it so that it applies to all species but that it only has a positive effect on members of the opposite sex but has an equal negative effect of members of the same sex.

I'm guessing you're using the Species Menagerie, but I can't find a version of it that matches what you're describing. With the rules that you're using, is it normally treated as a power/action or is it just an inherent trait that always applies?

From the version I have (the final one?):

Pheromones: As an Action, a Falleen can make a Deception check against a single target within Short range opposed by the target's Discipline, with each success dealing 1 Strain to the target. Targets that are immune to or are unaffected by atmospheric hazards are immune to this effect.

I think one of the earlier versions may have given Boosts to Social skills?

From the version I have (the final one?):

ed as a power/action or is it just an inherent trait that always applies?

Pheromones: As an Action, a Falleen can make a Deception check against a single target within Short range opposed by the target's Discipline, with each success dealing 1 Strain to the target. Targets that are immune to or are unaffected by atmospheric hazards are immune to this effect.

I think one of the earlier versions may have given Boosts to Social skills?

The OP also said that it was limited to humans, and I'm unable to find a version that contains that limitation.

I think I am just going to steal what ghostofman wrote.

Maybe I will use the force die. To give him setback or boost one the resilence check.

I am not quite sure I'm going to the determine the difficulty of the check.

I think I will upgrade the check if the ability is being used on something other than humans.

Off the top of my head, wouldn't it fail to work on Gand? What with their respiration system and all.

Off the top of my head, wouldn't it fail to work on Gand? What with their respiration system and all.

Gand are capable of chemoreception (smell and taste) even if they don't require gasses from the atmosphere. They are no more immune to pheromones than they are nerve toxins.

Off the top of my head, wouldn't it fail to work on Gand? What with their respiration system and all.

Gand are capable of chemoreception (smell and taste) even if they don't require gasses from the atmosphere. They are no more immune to pheromones than they are nerve toxins.

Well, Gands are able to cope with some toxins depending on how they work. Ooryl walks through some type of gas on Coruscant that would have knocked out his human companions. I don't remember the book getting too specific about the details so if it was comparable to pheromones is hard to say. I wouldn't grant Gands immunity to pheromones though; not being killed by something isn't the same thing as completely immune to it's effects. Maybe just add a setback to the check against them.