Considering the scenario:

NPC melee or ranged combat check against a PC. Average Difficulty level to start (two difficulty dice). The player is currently sustaining Force: Sense with the Strength upgrade to upgrade the difficulty of the pool twice. Now the Difficulty level is Daunting (four difficulty dice).

The PC then activates Dodge in which he has three ranks. This upgrades the difficulty of the combat check by three. The first upgrade would be to Formidable (five difficulty dice) but what about the remaining two difficulty upgrades?

The rules for checks the PCs make beyond Formidable recommend requiring a Destiny point be activated while the pool remains at Formidable.

Another option I had considered was upgrading the difficulty dice to challenge dice equal to the number of additional difficulty upgrades. The resulting difficult check would be three difficulty dice and two challenge dice.

What rule is appropriate in this case?

Thanks in advance.

You conflate "increase difficulty" with "upgrade". Upgrade means you swap a purple for a red. So first scenario you'd roll RR. Then, with three ranks in Dodge, you'd upgrade another three. Seeing as it's only average difficulty (RR), you'd increase difficulty, upgrade, then increase again. Final roll would be RRRP.

Exactly. Whenever something says "Upgrade the difficulty of..." it means "remove one Difficulty Die (purple) from the pool and replace it with a Challenge Die (red)."

What you're describing is INCREASING the difficulty, which is where you add more Difficulty Dice than normal to the pool. These are two different mechanics (although sometimes in order to Upgrade you need to Increase), so you have to pay attention to the abilities, talents, and maneuvers you're using to make sure you know which one is happening.

So, for your example:

We start with the melee difficulty, which is Average [ 2 Difficulty Dice ] ;

It is UPGRADED twice, because of the PC's Sense power, leaving us with a difficulty of Average [ 2 Challenge Dice ] ;

It is UPGRADED three more times because of the Dodge talent. Now, here, because we have no more Difficulty Dice to upgrade, the first new upgrade adds a Difficulty Die , then the second upgrade...uh, upgrades it...then the third adds another new Difficulty Die . This gives us a final difficulty of Daunting [ 3 Challenge Dice , 1 Difficulty Die ] .

You did get me on the right path but, further reading shows that Force: Sense upgrades the difficulty of the dice pool and Dodge increases the difficulty level of the combat check.

So you would first asses the difficulty of the check which would be Formidable (five difficulty dice, Average+Dodge rank 3) and then upgrade the dice pool with Force: Sense. The result being two challenge dice and three difficulty dice.

Thanks.

I'm looking at the description of the Dodge talent in my F&D Core book right now (page 142), and it says, "...then upgrade the difficulty of the combat check by that number."

I'm not sure where you got that Dodge increases the difficulty instead of upgrading it...

Double checked it too. Dodge definitely upgrades.

It does read upgrade. The distinction is the combat check in the case of Dodge and the dice pool in the case of Force: Sense. In your scenario you are applying dice pool modification rules to Dodge ranks.

Dodge reads that it upgrades the difficulty of the combat check. Which I believe you would associate with Defining Task Difficulty (FoD pg. 25)

It does read upgrade. The distinction is the combat check in the case of Dodge and the dice pool in the case of Force: Sense. In your scenario you are applying dice pool modification rules to Dodge ranks.

Dodge reads that it upgrades the difficulty of the combat check. Which I believe you would associate with Defining Task Difficulty (FoD pg. 25)

The attack's difficulty has already been defined for you: the difficulty of all melee-ranged combat checks is defined as Average [ 2 Difficulty Dice ] . It's in the chart on page 26, listed under the various combat skills on pages 129-131, and in a couple of other places I'm not remembering. Recall that the difficulty of a check is defined by the base action: outside circumstances, including items or weapons used, armor worn, and talents and powers used do not change the base difficulty of the check. They alter it by adding, subtracting, or upgrading dice, but the base difficulty is constant.

So, with the difficulty thus defined (Average), we then set about modifying it for the various powers and talents. Both the Sense power and the Dodge talent say they "upgrade" the base difficulty, so, using the "Upgrading and Downgrading Dice" rules on pages 29 and 30, we would see that our base difficulty of Average [ 2 Difficulty Dice ] would receive 5 upgrades, and become Daunting [ 3 Challenge Dice , 1 Difficulty Die ] .

If it were to work as you are suggesting, the Dodge talent would need to say that it increases the difficulty of the check, as that's the only way to make a check go from being defined as Average [ 2 Difficulty Dice ] difficulty to being rolled as Formidable [ 5 Difficulty Dice ] .

EDIT: Oh, I think I see where the confusion is coming from. There is no difference between "upgrades the difficulty of the pool," (as written in the description of the Sense Control upgrade) and "upgrade the difficulty of the combat check" (as written in the description of the Dodge talent). While the former is slightly less precise, both mean the exact same thing.

The combat check is performed by assembling a dice pool, which includes an ability portion (the Ability Dice and Proficiency Dice ) and a difficulty portion (the Difficulty Dice and Challenge Dice ). You can see this as all the sections that explain how to make a skill check (of which a combat check is a type) all fall under the major heading of "The Basic Dice Pool (pg. 24)." Both abilities (the Sense power and the Dodge talent) affect the difficulty portion of the pool in a specific way: upgrading the base difficulty a certain number of times.

Thanks.