As it stands, in the &{template:atk} field exists two conditions for hitting your target: "rname" (R-Name) and "rnamec" (R-Name C). rnamec checks if the base roll goes within the critical success threshold (commonly 20), and if so, to call a different ability than if it were to roll normally. However, I notice that there are no field options for an "rnamef" (R-Name F), to check if the roll is within a Critical Failure threshold. Roll 20 does support varying critical failure rolls via the cf argument (for critical failure, much the same as cs is for critical success), it would make sense if the template utilizing critical success checks the most had an option to utilize critical failures as well. Not all DMs are going to use Critical successes or failures of course, and normally Critical Failures don't add or subtract any dice, so I can see an argument for its exclusion since it doesn't really make much of a difference, however where it isn't useful in ordinary use, it can be vastly helpful for campaigns where Critical Failures have unique consequences as opposed to a regular or critically successful roll. Adding that would add a third ability call which can contain anything. It'd enhance the experience for those who wish for it, and I think it would be a great addition overall.