What is required to become a rogue?

[Kyoskai]

You can use lancer and pugilist cross-class skills, with rogue. so you might want to lv pgl to 15 for ninja, and also internal release (crit buff) at lv 12. And mantra at lv 42 (not really needed, but should be nice with Mug, to get more hp)
for lancer, you might want to lv it to 22, for invigorate, and lv32 to get blood for blood.

Mug heals for 50% of the damage, mantra wouldn't have any effect.