One says that characters can use an additional team ability. The other says they can't. Which takes priority?

Can't trumps can. But they also work independently. Stryfe ONLY grants BoM TA IF the target's can't use another TA. SInce Cypher makes it so that they CAN USE another TA, then Stryfe's power gets hosed.

To me, I see two things happening.

1.) Stryfe takes away any original TA they had printed on the dial (if any), which is where the "can't use another ta" comes in.
2.) Cypher grants a TA that they can use in addition to Stryfe's.

But I can see it ruled otherwise as well, with can't being interpreted totally and completely. What's causing the confusion then, is the "in addition" part of Cypher's text. They have a team ability (from Stryfe), and they can use Cypher's Team ability in addition.

Hurm.

LEADER OF THE DISPOSSESSED: Stryfe can use Leadership. At the beginning of the game, choose up to 5 friendly characters. Those characters possess the Brotherhood of Mutants team ability as long as Stryfe has not been KO'd and they can't use another team ability.

The bolded part is only the requirement for Stryfe to grant the BoM TA....not the effect of doing so. Stryfe never "takes away" any abilities, he's just checking to see if you can use any before he grants you one.

It says they possess the Brotherhood team ability as long as they can't use another team ability. Cypher effectively neutralizes this trait when he grants them the ability to use the one he gives them.

I see what you saw, and at first thought Stryfe made it so they couldn't use other team abilities, but his power means the same as this:

LEADER OF THE DISPOSSESSED: Stryfe can use Leadership. At the beginning of the game, choose up to 5 friendly characters. Those characters possess the Brotherhood of Mutants team ability as long as they can't use another team ability and Stryfe has not been KO'd.

A comma (maybe) or putting the "they can't use another team ability" into a different sentence would have totally changed the meaning.

Your points are both valid but I just can't see passed the bolded below:

LEADER OF THE DISPOSSESSED: Stryfe can use Leadership. At the beginning of the game, choose up to 5 friendly characters. Those characters possess the Brotherhood of Mutants team ability as long as Stryfe has not been KO'd and they can't use another team ability.

It's not just that can't trumps can, it is also that the power says another not their own or additional. So not only is Strye's saying can't but it is broad and sweeping not confined or specific, as I see it.

"They can't use another team ability" is a condition they must meet for them to possess the Brotherhood team ability, not a restriction on what they can do after being granted it. If a character on Stryfe's team already has the Avengers team ability, then Stryfe can't give them the Brotherhood team ability. He doesn't take away their ability to use the Avengers team ability, even if he chooses them.

Ok I think I see what you guys are saying now. You are reading it as two specific conditions. I would love to find out the actual intent of this because I have always thought it was an addition to the end not a condition to be met.

Exactly. They are conditions to be met.

For it to work the way you are arguing, it would likely have been phrased as:

LEADER OF THE DISPOSSESSED: Stryfe can use Leadership. At the beginning of the game, choose up to 5 friendly characters. Those characters possess the Brotherhood of Mutants team ability AND CAN"T USE ANOTHER TEAM ABILITY as long as Stryfe has not been KO'd.

Wow glad I stumbled into this one because I obviously had been misunderstanding that power for awhile now. Thank you guys for the help.

Yeah, I always played this power way wrong. I assumed the only characters he could choose were ones that didn't already have TA's (or were assigned ATA's).

I didn't realize you choose a character with a TA, but they just couldn't use it. Interesting.

Doesn't seem very to matter too much, as I can't see a ton of situations where you would want to trade your TA for BoM (big swarm teams I guess), but nice to know.

No, they can't. This is a good summary here:

Ok good, phew. I wasn't playing it wrong. Thanks.

So am I correct in my understanding?

At the beginning of the game I choose which goes first. So I choose to use Stryfe to give all unaffiliated friendlies Brotherhood. I then have Cypher steal Mystics from my opponent. Now those unaffiliated have both Brotherhood and Mystics.