[RPG] Does the Resilient (Con) feat or the War Caster feat most improve the chances of maintaining concentration


The Resilient feat (PHB, p. 168) allows you to increase one ability score by 1 and gain proficiency in saving throws using the corresponding ability. In essence, taking the Resilient feat and picking Constitution adds a flat bonus to all Constitution saving throws, increasing from +2 to +6 as you gain levels.

The War Caster feat (PHB, p. 170), among other benefits, grants advantage on Constitution saving throws that you make to maintain your concentration on a spell when you take damage.

It seems like War Caster would improve the consistency of passing most Concentration checks, but that Resilient (Con) would improve the chances of passing when taking larger amounts of damage that result in a higher DC check.

Which of these two feats statistically provides a greater benefit in helping a character maintain concentration on a spell?

Best Answer

The proficiency bonus is the primary factor

I made a graph to compare Resilient and War Caster.

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How to read the graph.

The horizontal axis is the save DC, the vertical axis is the chance of success, where 1 is guaranteed success and 0 is guaranteed failure.

War Caster is blue, Resilient is red, and no-feat is green. The lines are also labeled accordingly, with the "+number" being the bonus to the save. The constitution modifier is set to 1 by default1.

There are six red lines because there are five proficiency values (2 through 6) plus another bonus if resilient improved your constitution modifier. For example, if you have 13 constitution and are advancing to level 8, then your save with Resilient would become 2 Con + 3 Prof. Therefore, you compare the blue +1 line with the red +5 line.

Resilient vs War Caster comparison.

For the purpose of concentration checks, if Resilient improves your concentration by at least 5, then Resilient is strictly better than War Caster. This is the case if your proficiency is at least 5, or if your proficiency is 4 and Resilient also improves your constitution modifier.

For the purpose of concentration checks, if Resilient improves your concentration by at most 4, then War Caster is usually (but not strictly) better than Resilient. There are a number of unusual circumstances that can skew the choice in Resilient's favor, especially if more than one applies to you. For example:

  • If you are starting at a level where War Caster would be better, but you know that the majority of the campaign will be played at levels where Resilient is better.
  • If Resilient (in combination with features such as Aura of Protection or Bladesong) would enable a concentration bonus of at least 9, because it would guarantee passing the minimum save DC.
  • If you often lose concentration by falling unconscious (rather than by failing concentration checks) and Resilient would increase your HP, because that extra HP can occasionally allow you to stay conscious and therefore concentrate.
  • If you receive damage is large chunks such that the save DC is very often over 15+Con, because beyond that threshold War Caster's benefits lessen noticeably.
  • If you very often receive damage through Constitution saving throws, because you will more often reduce these sources of damage and therefore the concentration save DC will be smaller.

  1. The graph is somewhat interactive: it has a slider called con with which you can easily change the constitution modifier.