Does Decider do anything?

It's spelled out on the mechanics page. It's pretty weird.

The wording in it is somewhat confused. I think the rulebook text I'd suggest for Decider would be:

> If a player has a choice whether or not to take an action during the resolution of an ability of a permanent with Decider, that player flips a coin. If they win the flip they must take the action and pay any costs if able. If they lose the flip they must not take that action.

Reminder text is a bit trickier... perhaps something like

> Decider (If this permanent's abilities give you a choice whether to take an action, you must flip a coin to see which choice to make.)

Note by the way that the "pay all costs if able" clause doesn't really work, because you can't force players to tap lands for mana, so it only works for costs like "Discard a card" or "Sacrifice a creature".

Nice idea for a mechanic; only half the time do they do anything - but one in eight - woo!

On the flip side; as the card set says - this is an inadvisable mechanic. Chance is bad, and three sets of coin flips in a row is trebly annoying.

This is best used with cards that can inherit the activated ability alone, without the awful excess baggage that goes with it. Stuff like Skill Borrower or Dark Impostor.

Thanks Alex, thats actually a more concise way to put it. We are actually 2-3 people working on this "bad mechanics" set, so trying to hammer out robust rules text is a pain sometimes.

@SadisticMystic: Yeah, hadnt even though of that. Definitely makes for an interesting deck design - alternatively, theres other cards in the set that play around with Decider as a keyword, either imparting or stripping it, so there's a lot to be played with.