Let me explain how this feat really shines with warlock spellcasting, because it's actually quite fascinating. You'll find that maintaining concentration becomes significantly easier, which is crucial since warlocks only have those precious few spell slots to work with (making each spell count is essential). When you're focusing on spells like hex or hunger of hadar, you'll get advantage on constitution saves whenever something tries to break your concentration, and believe me, that's going to happen a lot in tougher fights.

Something interesting you might not have considered is how this works particularly well for blade pact warlocks, since they're often in the thick of combat. You'll get to use shocking grasp as a reaction when enemies try to move away from you, which can really mess up their plans. Sure, it's not as flexible as the tabletop version, but it's still pretty effective when you need that extra bit of control.

I should mention that while war caster is fantastic early on, some players prefer resilient constitution for later levels because it scales differently with your proficiency bonus. But here's the thing - if you're running a concentration-heavy build, especially one that puts you near enemies, war caster might just be your best friend. The advantage on concentration saves combined with that reactive shocking grasp can really turn the tide of battle when you least expect it (and those moments when you stop an enemy from reaching your squishier allies are just perfect).