For bossing Get HK merc all decked up with all passive skills maxed. Focus on getting evasion, magic evasion and cri evasion before increasing defense mastery.
Then get as many evasion passives from Rameda as well. No need for Robust since A5 is already pretty good. Put 1000 points in DEX and then boost health till 4.5K for Hatrel bossing. Put rest in INT. For Clorence, get RB12 A5 and use the same strategy but get HP bar to 6.5k or more based on how fast you can pot. Clorence requires skill for solo bossing, you can't waltz in like you do in Hatrel.
Ranias is a different story, someone else can elaborate on taking that down.
Anyone can share how to build a full PVE mage? more to bossing and grinding. how much on INT, DEX and VIT? What passive skills should i add? Mercy stats and passive skills as well. RB12 Level165 Mage here thankyou.