Yesterday I decided to go for some quick testing of some mechanics as Sinkiang, and then I decided to just go and continue playing (damn you HoI IV). While playing as Sinkiang, then turning into PRoC, I've decided to go and try to grab that Sun Tzu Reborn achievement. And lo' and behold here it is - Sun Tzu Reborn is here.
@podcat , @shultays - I'm tagging you, because I have some weird observations with the new XP system, they'll be in the last paragraph of the text - If you don't want to read it all, just skip to the 'last' part.
Here is our brave Field Marshal who became new Sun Tzu, writing Art of War 2: Electric Boogaloo
Price of the achievement?
(Spain and Romania ruined my stats, by being splinter civil wars from Commintern members). Anyways, I would say it's quite decent trade, 2.83 M against ~67M.
After securing China and Japan as Sinkiang (ez-pz) I decided to pull the trigger on both Allies and Commintern (Axis was long dead, though weirdly enough they retained few states as German Reich who then flipped into Socialist Republic of Germany) and Slovakia. Bonus points for weirdness: East Germany and West Germany also existed, Poland ended up owning Ostpreussen and Danzig, while Former German Reich had Munich and parts of the Poland proper. In this three way conflict, Commintern started pouncing on allies pretty hard, and sudden civil war in USA (Communist one) basically was a final nail to the coffin for allies. Allies soon capitulated and Commintern become leading power - at this point war remained between me, world lead by Commintern and Allies, consisting of capitulated West Germany and Ireland. So I did procced to go and deal with Commintern. After some 67 M dead, achievement was earned.
Now let's look for the Field Marshal and his army stats
Notice how I said army? I decided to go for FM leading army route. Also light tank divisions are still in style, and screw you - medium, modern, heavy tanks
. Why leading army? Because this way you accumulate normal amount of experience from eliminating pockets,encirclements, instead of getting only quarter of it. (Field Marshals leading army group earn 25% of the experience their generals get) - and that will be prime amount of the experience to level up. Grinding experience through head-on attacks is just futile attempt to get level 9. (Unless I guess you'll setup yourself across the maginot line, press attack and then just go AFK watch Band of Brothers for sixteenth time - there is however chance you'll end up in Paris with barely any progress in XP bar).
Now observations and couple suggestions/advice:
1) Whenever you want to eliminate pocket, do it with all the divisions in the army, weirdly enough - XP scales for eliminating enemy divisions in encirclements, with both the number of their divisions AND yours participating in combat. As a test you can for example place all the Red Army starting divisions in one province and then destroy them. If you'll use 1 division, you will gain 40 XP or so, while using 24 divisions will net you much, much more XP.
2) If you want to drink all the delicious XP, do not use other leaders divisions in the process of eliminating of pocket (or at least the final mop-up battle), otherwise XP gained is SHARED. You don't want to share, right?
3) Leader while he is still 'reassigning' despite not providing any benefits, will still drink up XP gained from the fight, so if you don't want/can't spare certain army to go towards the target you want, you can just go and reassign the leader to the army that can mop-up the encirclement.
4) Be flexible, if you're for example under heavy enemy attack everywhere in certain army group, don't be afraid to assign FM to lead that army group for now, with 5 armies under constant attack he will get up to 1.25/1.75 single army general would earn (depending if you picked Army Delegator FM trait). XP gained from regular combat after a certain point is rather small compared to what you need, but you can still get more of it.
5) Try as much as possible to get Skilled Staffer ASAP - it gives extra 6 divisions - and as such you'll get more XP per each hour of combat
Now TL
R - For @podcat and @shultays (if I should tag someone else, please let me know)
1) It's weird that you gain more experience from eliminating pocket with more your divisions participating in combat. If I will use 1 division to eliminate enemy 138 divisions I will gain miniscule amount of experience, compared to what I would get if I would use 24 divisions. And by that I mean divisions participating in combat, so you want always eliminate pockets with 24 divisions in current system. No matter if 19 or so divisions will be in reserve or so
2) There is also weird behaviour with XP/traits system sometimes - For example if I will use 24 divisions to eliminate that said 138 division pocket. If I will attack across the river, from only one direction (more divisions in the reserve) I will get for example 801 XP towards Infantry Leader (some are gained from 4 hour-fighting window).
However if I'll attack from several directions, with more divisions in the actual combat, I'll get 725 XP toward Infantry Leader.
When I'll atack from one direction, but not across the river, I'm getting 849 XP toward Infantry Leader.
That's why:
3) Please, can you share the exact formula, how it should be calculated/work? I'm either having for the first time problem with simple numbers, or missing something obvious (or famous PDX math in action) - anyways, I'm lost in how exact XP numbers are generated. Whenever I seem to (based on defines and observations) to get the exact amount of XP in one case, there shows another case where it doesn't match at all.
I'll also upload the test save where you can test the encirclements - don't forget to turn off AI with console just in case
And that's it for now. If I'll remember something, I'll add to it.

@podcat , @shultays - I'm tagging you, because I have some weird observations with the new XP system, they'll be in the last paragraph of the text - If you don't want to read it all, just skip to the 'last' part.
Here is our brave Field Marshal who became new Sun Tzu, writing Art of War 2: Electric Boogaloo

Price of the achievement?

(Spain and Romania ruined my stats, by being splinter civil wars from Commintern members). Anyways, I would say it's quite decent trade, 2.83 M against ~67M.
After securing China and Japan as Sinkiang (ez-pz) I decided to pull the trigger on both Allies and Commintern (Axis was long dead, though weirdly enough they retained few states as German Reich who then flipped into Socialist Republic of Germany) and Slovakia. Bonus points for weirdness: East Germany and West Germany also existed, Poland ended up owning Ostpreussen and Danzig, while Former German Reich had Munich and parts of the Poland proper. In this three way conflict, Commintern started pouncing on allies pretty hard, and sudden civil war in USA (Communist one) basically was a final nail to the coffin for allies. Allies soon capitulated and Commintern become leading power - at this point war remained between me, world lead by Commintern and Allies, consisting of capitulated West Germany and Ireland. So I did procced to go and deal with Commintern. After some 67 M dead, achievement was earned.
Now let's look for the Field Marshal and his army stats

Notice how I said army? I decided to go for FM leading army route. Also light tank divisions are still in style, and screw you - medium, modern, heavy tanks
Now observations and couple suggestions/advice:
1) Whenever you want to eliminate pocket, do it with all the divisions in the army, weirdly enough - XP scales for eliminating enemy divisions in encirclements, with both the number of their divisions AND yours participating in combat. As a test you can for example place all the Red Army starting divisions in one province and then destroy them. If you'll use 1 division, you will gain 40 XP or so, while using 24 divisions will net you much, much more XP.
2) If you want to drink all the delicious XP, do not use other leaders divisions in the process of eliminating of pocket (or at least the final mop-up battle), otherwise XP gained is SHARED. You don't want to share, right?
3) Leader while he is still 'reassigning' despite not providing any benefits, will still drink up XP gained from the fight, so if you don't want/can't spare certain army to go towards the target you want, you can just go and reassign the leader to the army that can mop-up the encirclement.
4) Be flexible, if you're for example under heavy enemy attack everywhere in certain army group, don't be afraid to assign FM to lead that army group for now, with 5 armies under constant attack he will get up to 1.25/1.75 single army general would earn (depending if you picked Army Delegator FM trait). XP gained from regular combat after a certain point is rather small compared to what you need, but you can still get more of it.
5) Try as much as possible to get Skilled Staffer ASAP - it gives extra 6 divisions - and as such you'll get more XP per each hour of combat
Now TL
1) It's weird that you gain more experience from eliminating pocket with more your divisions participating in combat. If I will use 1 division to eliminate enemy 138 divisions I will gain miniscule amount of experience, compared to what I would get if I would use 24 divisions. And by that I mean divisions participating in combat, so you want always eliminate pockets with 24 divisions in current system. No matter if 19 or so divisions will be in reserve or so
2) There is also weird behaviour with XP/traits system sometimes - For example if I will use 24 divisions to eliminate that said 138 division pocket. If I will attack across the river, from only one direction (more divisions in the reserve) I will get for example 801 XP towards Infantry Leader (some are gained from 4 hour-fighting window).
However if I'll attack from several directions, with more divisions in the actual combat, I'll get 725 XP toward Infantry Leader.
When I'll atack from one direction, but not across the river, I'm getting 849 XP toward Infantry Leader.
That's why:
3) Please, can you share the exact formula, how it should be calculated/work? I'm either having for the first time problem with simple numbers, or missing something obvious (or famous PDX math in action) - anyways, I'm lost in how exact XP numbers are generated. Whenever I seem to (based on defines and observations) to get the exact amount of XP in one case, there shows another case where it doesn't match at all.
I'll also upload the test save where you can test the encirclements - don't forget to turn off AI with console just in case
And that's it for now. If I'll remember something, I'll add to it.