Paladin weakest Tank now

[Ryaduera]

and DRK still has the best Tank CD in the game.

Except it doesn't. Let's just say a tank buster does 75% of a tanks max HP as damage. Let's pick a nice and simple but realistic number to be the tanks HP at 70,000. Now keep in mind, a 75% tank buster is by all means a weak tank buster. Extreme, Savage, and Ultimate content will always outright kill a tank that did not use a mitigation. This will be important later.

We can ignore Ramparts and Shadow Wall for this as each tank has equal abilities to consider.

75% of 70,000 is 52,500 so we can use this as the damage the tankbuster is doing. Considering only the unique cooldowns DRK has access to we can easily calculate just how much mitigation this is. The good thing about TBN is that being a shield it doesn't actually suffer from diminishing returns, it's basically just increasing your max HP in effect. The math here is easy. 25% of 70,000 is 17,500 and Oblation reduces the tank buster by 10% for a value of 5,250. You reduce the tankbusters damage down by effectively 22,750, for an overall damage total of 29,750 damage going through, Result, your DRK HP is now at 40,250/70000

Now let's look at GNB Heart of Corundum. There's actually something a little funny in the way this mitigation works, since the initial mitigation and the 4 second bonus are separate buffs they actually suffer from diminishing returns. No big deal, easy math, you lose overall 2.25% mitigation (15% of 15 is the loss here) for a total mitigation of 27.75% damage reduction. This reduces the damage by 14569 (14568.75 rounded up) dealing 37931 damage leaving our GNB at 32069/70000. Technically, this is less mitigation, however anything that drops the GNB below half health will activate their heal, which on my GNB is 11,000 ~ 12,000 HP healed after the damage done. Let's round it down so I don't accidentally inflate the math here, down to 10,000. This still leaves us at 42,069/70,000, more than the DRK has after the same tankbuster.

This puts us at 40,250 on the DRK and 42069 on the GNB for a difference of 1,819 more HP on the GNB. But there's more. Like I said, 75% of max HP is a pretty weak tank busters as most relevant content tank busters will just outright kill a tank that doesn't mitigate. Let's take the same values and mitigations for a tank buster that would deal all 70,000 of the tanks HP and look at the difference.

DRK: 70,000x 0.10 =7,000 Oblation mitigation. 17,500 blocked by TBN. 24,500 total damage mitigated. Total damage dealt: 45500.

GNB: 70,000x 0.2775 =19,425 Heart of Corundum mitigation and total damage blocked. 10,000 Hp healed after. 29425 total damage mitigated. Total damage dealt: 40575.

DRK remaining HP is 24500
GNB remaining HP is 29425
Difference: 4925

You can see the way the math works out the more damage a tank takes the weaker TBN is by comparison. The literal only thing keeping TBN even somewhat mentionable next to he other skills is it's cooldown, but it's a DPS loss to not break it and also tied to a resource you need to balance. You are putting in more effort to keep your MP up for less reward. And this is without even mentioning that this math included a second cooldown in favor of the DRK. The larger the damage taken, the more favorable HoC is over pairing TBN with Oblation. The problem is that TBN will only ever mitigate the same amount of hp in complete disregard of the amount of damage taken. TBN is only good if the tank is taking less damage. Do keep in mind, the math adds up even in the case of multiple strikes as long as it falls within the 4 second window, after that, multi-strike mitigation math gets more complex.

Now, there is something that must be said. TBN can in theory save you where HoC can't. In order to take the heal from HoC, you must first survive the initial damage, where TBN is essentially an increase in max HP. The problem lies in the fact that in order for the other 3 tanks to be tanks this scenario cannot exist within the games content. If this scenario did exist, DRK would just be mandatory for the content no matter what, and Squeenix won't do that for any role, especially not tanks. The only exception being that if TBN is being placed on either a squishier DPS/healer that made a mistake on a mechanic, or a tank that has vulnerability stacks, in which case TBN may actually be preferable, but you could also just... Learn the fight... The only scenario in which TBN is better is when damage is either negligible, or one brought about by mistakes in ones gameplay.TBN is a great skill, especially when paired with other mitigations, but DRK just... doesn't get other mitigations. Dark Mind? Not good. Camouflage on the same GNB is 10% damage reduction, straight up, as well as a parry rate, being doubly better than Dark Mind. Dark Passenger? We have the same thing in Heart of Light.

Also, I don't normally add chance to a discussion like this since I absolutely hate chance, but I think it has some relevance here since the chance here works in favor of the skill that is already better. TBN cannot crit. The heal from HoC can. That is very worth considering. The skill that is already consistently a better performer has a chance to perform even better. Rest in Pieces Dark Knight. Petition to birng back a modernized version of Sole Survivor.