Stacked Catch now reads:
Stacked Catch [+varies]. Normally, all your Toughness powers can only receive the refresh rebate effect of one Catch, so you line them all up and choose the best one. If you take Physical Immunity, and have other Toughness abilities already covered by a Catch, you may also receive the refresh rebate of a second Catch. This second Catch may only affect how the Physical Immunity works, and it’s called a Stacked Catch. If you take a Stacked Catch, the first Catch covering the other Toughness powers does not include the Physical Immunity as one of the abilities covered.
For example, let’s say a fire demon has Supernatural Toughness with the Catch that he’s vulnerable to cold. Normally, this would give him a refresh rebate of +3: +2 because cold is easy to come by, and +1 because research would normally uncover it.
In addition, he has physical immunity to damage from any kind of fire. The Catch is that it only applies to attacks with fire. Normally, this would give a rebate of +5: +2 for protecting against only one specific thing, +2 because “not fire” is easy to come by, and +1 because research would normally uncover it.
Because you can stack these two refresh benefits, the demon gets a total of +8 toward his Toughness powers, so his total refresh cost is only –4 (–4 for Supernatural Toughness, –8 for Physical Immunity, +8 for the stacked benefit).
A character with a Stacked Catch that that inverts the conditions of the first Catch is strongly discouraged. A Physical Immunity to Fire layered on top of Supernatural Toughness that can only be pierced by Fire just never happens in reality, and if it did, one or both Catches would be rightly valued as worth zero.