quippe

Quippe is an emphasising particle, "of course, naturally, obviously", and it very often carries a sneer: the speaker is pointing out something the other side should have worked out for themselves. It usually stands first in its clause, unlike enim and autem, which must come second.

The construction to learn is quippe qui with the subjunctive, a causal relative clause meaning "seeing that he", "inasmuch as he" - non venit, quippe qui hostis esset. Sallust and Livy use it constantly. Outside that pattern quippe explains rather than joins: it colours a statement that is already there, where nam and enim actually link one clause to another. Read it as "obviously" and you will rarely be far off.