Is there any rationale for getting Titan records/books? For example, do I need to finish a WBU with combat character to get a combat titan records or is it completely rng?
It’s not COMPLETELY RNG. Proxima drops combat books, Cull drops blast books, Corvus drops speed books, and Ebony drops universal books. Thanos can drop any. However, it IS RNG regarding when and if they drop.
It's completely RNG.