Did X-Risks change biomorph infection rolls?

Question

So X-Risks is out, and does a lot to define the rolls to resist exsurgent infection. Some of these apply to info previously in core or elsewhere, particularly so for the below:

A biomorph exposed to this infection must make a DUR × 2 Test to determine if the infection takes hold. Basic biomods and nanophages do not offer any protection, though toxin filters (p.  305) and medichines (p. 308) each give a +30 bonus (though it is likely only a matter of time before a mutant exsurgent strain learns to bypass them). If the test fails, the victim is infected. (Core, 364)

Exposed biomorphs must make an Opposed Test, pitting their Durability vs. the pathogen’s Infection Rating. Toxin filters and medichines provide a +30 bonus. If the pathogen wins, they are infected. (X-Risks, 171)

There's some other guidelines that up the difficulty to a degree but going from DUR×2 to DUR rolls is the biggest potential concern. Given problems sometimes in other books I was wondering if anyone knew whether this is meant to be an intentional nerf of the core's resist chances, a mistake, or neither (making it an opposed check may weaken the probability of things leading to a need to cut the DUR roll in half)?

Answer 1

It's hard to know the answer with 100% reliability without asking the authors. However, I think the most likely answer for the purpose of actual practical GMing is 'neither', and here's why:

• It is canonical that Exsurgent has many strains which vary.
• In fact the first quote of yours points out that a strain may evolve (or already exist!) that ignores some of the modifiers.
• Different campaigns warrant different levels of threat from hazards such as infections.
• Different groups may be more happy about different amounts of rolling - some people prefer strictly player-facing rolls and so would benefit from a non-opposed mechanic, while others feel more invested if there's dice flying around the room.

As a result, I think the 'neither' answer is of the 'optional rule' flavour. Many systems have rules marked or implicitly optional, to be used or discarded depending on the needs of the campaign. While not marked explicitly, I think in this case it should be treated as such.