<requirement /> works on gamestages.xml?

[Chicxulub]

If I try to add a custom group of zombies to a blood moon based on a certain requirement, such as probability, could that work? Something like this:

<gamestage stage="40">
<spawn group="DemolisherOnlyGroup" num="100" maxAlive="100" duration="1" interval="10">
<requirement name="RandomRoll" seed_type="Random" min_max="0,100" operation="GTE" value="50"/>
</spawn>
<spawn group="feralHordeStageGS31" num="57" maxAlive="15" duration="1" interval="28"/>
<spawn group="feralHordeStageGS35" num="57" maxAlive="15" duration="1" interval="10"/>
<spawn group="feralHordeStageGS40" num="57" maxAlive="15" duration="1"/>
<spawn group="feralHordeStageGS40" num="999" maxAlive="10"/>
</gamestage>