I’m no master, but if it were me making an actual Chaplain-PD2, I’d distribute things exactly like this:
Lv1 Safety Zone + the attribute from Cleric 2 would be more than enough.
Lv5 Divine Might (I’d get a Corylus Gem as well) is a must and you will use and abuse this skill all the time. It also helps align your Aspergillium duration with Blessing for easier micro-management of your buffs.
Lv1 Sacrament for people that may ask for the extra line, or if you find yourself running out of the bought buffs from Pardoners (you should just buy their Lv17 Aspersion and Lv12 Sacrament anyway).
Lv7 Revive +1 from Divine Might grants 8 seconds of immunity after pseudo-death. It’s more than enough.
Lv10 Mass Heal because it’s percentage based, with Divine Might it’s 30% + your INT (and SPR, but since you’re mostly INT I won’t bother with the calculation). As a 100% INT Chaplain myself, my Mass Heal is ridiculously strong.
Hanaming Gem is expected so you get that nice and even 12 Heal tiles after Divine Might. Also, since you’re INT, you will be using Heal and Cure to burst down bosses (works on flying, as long as it’s a boss).
At R7, you should be wearing an Agny Necklace or get yourself one as soon as possible. Incineration should be upped to Lv5 ASAP. You will have to get creative with how you generate debuffs on your target though seeing as you only have Monstrance (which doesn’t work on all targets) and Exorcise (which actually stays as a DoT on your target even after you’ve triggered Magnus) as well as Cure (which has a hit limit + doesn’t work on flying mobs, bosses are fine).
At R8, you just need to use Black Death Stream (Plague Vapors) right off the gate, then Incinerate. Your target will be likely dead before your second overheat gets used anyway.
Lv5 Bloodletting (MAX) + 1 via Divine Might let’s you forget about any Rank 1 and Rank 2 debuffs that are headed your way. 100% uptime, works well with parties too.
Lv5 Healing Factor + 1 via Divine Might helps you tackle stuff even if you’re naked (provided you don’t get one shot or overrun). It just heals and heals and heals. 100% uptime at Lv6 (hence DM)
Last 5 points in PD2 are yours to decide on.
So basically at the start of your play session, buy Lv17 Aspersion and Lv11/12 Sacrament from Pardoners. For combat, before initiating, you will cast Divine Might, then Aspergillum, Blessing (which still reaches +456 and higher despite having 0 SPR invested), Last Rites then Bloodletting if you’re expecting a lot of debuffs. Else it’s just a matter of keeping Aspergillum and Blessing up and occasionally rebuffing Last Rites.
Revive is up to your preference. I rarely use mine because my P.Def is at 3500+ and M.Def is at 3000+. I use it when I go with randoms for 290 rushes though. I usually let them get hit first (because I like it like that) to gauge their softness. If they go down 50%+, one Mass Heal will bump them to max health again (even if MH only heals 30%, the extra is from my 859 INT and some SPR), then I use Revive.
I have a PD2 myself, although it’s built around my Pardoner (which I use for personal scroll making). So my experience is coming from two areas.
Should you decide to pursue Miko and then go PD2. You will be missing out on all the benefits of Cleric 2 because your build will definitely be: C1-P3-Cha-Mik-PD2. So there’s that.
As an INT based character, the extra 1 Level to all skill you get for your next 5 or 6 skills (depending on whether you have Corylus Gem) will have a great effect on your DPS.
Also, having Cure’s attribute for hit frequency (available at Cleric C2) is a must if you want to burst using it. The extra levels adds damage too, seeing as you’re INT based, that’s a lot. Heal at high levels hit like a truck mind you (especially while under Blessing of any level).