There are currently no nightly builds for wildfly-core available.
We are working on progress for new public CI system that will be available on ci.wildfly.org that will allow us to provide this as well...
For time being I can only recommend you to build it manually.
mvn clean install -Prelease -DskipTests
this way you will get zip distributions in dist/target
We published our public CI and you can now grab WildFly core nightly builds from there.
for latest finished build:
or to see history of nightly builds https://ci.wildfly.org/viewType.html?buildTypeId=WildFlyCore_Nightly
for login you can use guest login
for example downloading latest successful nightly build zip you can use url