How about giving cp4 sector arty

(why its 560, I fail to understand)

That's why:
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Instead of adjusting the 10% DR to accomodate the stug, you could simply increase stug health to 600 or 640 like a proper medium. (why its 560, I fail to understand).

Back on topic.. This version of mark target is fail because

1: Pak already has very very good pen and allied tanks short of is2 cant stand pak fire for long so armor debuff makes no sense to me. Panther has 220 pen already and stug also has 180? which is good enough

2: The only usable scenario I see is maybe marking the t70 so that the pak can reliably hit it, but this defeats the point because by then you already have a higher tier and tank out.

Like I actually want to know what scenarios you guys have in mind concerning this tank and this ability.

personally.. id like the cp4 to call in flares like that command panther will. no need mark target no smoke no thing else is needed.

The StuG survives three shots but then dies to a snare, which makes it slightly weaker than a medium that would survive a snare and three shots. At this strength, the StuG can reliably fight mediums while being weaker when a snare threatens it.

Regarding the CP4: The ability will still come in handy for T3 P4 builds as well as when facing Soviet doctrinal armor as well as late game UKF. If it is worth it for the accuracy (which will help in almost any setup) alone is debatable, but it fits the role of complementing other units. It'll make a medium only rarely miss its target, at least when stationary

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Like I actually want to know what scenarios you guys have in mind concerning this tank and this ability.

granted there might not be too many situations where getting a cmnd.p4 + mark target will straight out beat just getting a regular p4 instead, but there are some for sure. those will mostly involve t3 units pitted against heavier armored vehicles, as hannibal already elaborated, though not entirely.

if my simplified back-of-the-envelope calculations (long range pen, frontal armor, assuming 100% acc) are not too far off, a cmnd.p4 + panther + mark target combo deals virtually the same DPS against an IS-2 as a regular p4 + panther during the 30 s the ability is active. granted this isn't long enough for a vet0 panther to score a kill as you'd only get max 5 shots off before mark target expires, but it'll still heavily shift the odds in your favor. and that is neither considering the accuracy buff nor the survivability bonus you get on top of the better penetration, yet.

similarly, two p4s plus a cmnd.p4 with mark target will dish out more damage per second against a kv-1 or bigger (against any tank, in fact, that has at least 33% more armor than the p4 has pen) than three p4s could in the 30 s window the ability is active, again even before the DPS boost from accuracy.

so, yes, a cmnd.p4 just for mark target may not always be worth building over g a regular one, but there are certainly a lot of scenarios where that makes sense.

granted there might not be too many situations where getting a cmnd.p4 + mark target will straight out beat just getting a regular p4 instead, but there are some for sure. those will mostly involve t3 units pitted against heavier armored vehicles, as hannibal already elaborated, though not entirely.

if my simplified back-of-the-envelope calculations (long range pen, frontal armor, assuming 100% acc) are not too far off, a cmnd.p4 + panther + mark target combo deals virtually the same DPS against an IS-2 as a regular p4 + panther during the 30 s the ability is active. granted this isn't long enough for a vet0 panther to score a kill as you'd only get max 5 shots off before mark target expires, but it'll still heavily shift the odds in your favor. and that is neither considering the accuracy buff nor the survivability bonus you get on top of the better penetration, yet.

similarly, two p4s plus a cmnd.p4 with mark target will dish out more damage per second against a kv-1 or bigger (against any tank, in fact, that has at least 33% more armor than the p4 has pen) than three p4s could in the 30 s window the ability is active, again even before the DPS boost from accuracy.

so, yes, a cmnd.p4 just for mark target may not always be worth building over g a regular one, but there are certainly a lot of scenarios where that makes sense.

reasonable points.. fine

buffing the cp4 in any way is a big mistake (imo no bm)