Solved! It's a bit unfair that W requires some knowledge about <rot13>cebtenzzvat ynathntrf</rot13>. Also an unintended solution of B is <rot13>yrggre F zrnavat gur fhpprffbe, pbzzbayl hfrq va cebivat onfvp cebcregvrf bs Angheny ahzoref sebz Crnab Nkvbzf</rot13>, although that doesn't fit the final expression.