Good uses for Grim Feast?

Hi, kids. I'm playing a minion witch (Lich ascendancy, if you're curious) and I'm just basically trying stuff out on it as I play through. Decided to give Grim Feast a try. I'm sort of baffled. I understand how it works, but in practice it seems fairly useless. I've been buffing my minions via passives, so unless I'm against a boss or a very tough rare monster, they don't die much. The highest I've seen my "resurrection meter" get to is 39%. And that was during a boss fight. Nowhere close to being able to hit the "rise, Lord Vader, mwahahaha" button, so to speak.

Oh, and also, the "resurrection meter" goes down sometimes. Earlier today it was at 13%, then went down to 3%. Which was a surprise. Not sure how that happened. It's possible I misread it when it said 13%, but I don't think so.

I am getting some use out of Grim Feast via the support gems I'm using, which boost my mana regen (sorely needed since I took the ascendancy skill that causes my mana to drain constantly) and allow me to blow up my minions at any time, which is hilariously fun.

I just don't see any big benefit from Grim Feast itself. Maybe it becomes useful in more difficult content? I'm just in Act 3, which is fairly easy.

One notion I had was to use it to resurrect my Unearth minions, but I suspect that won't work because a) their deaths don't generate remnants and b) I don't think those bug minions are resurrect-able. Plus, Unearth is a mana hog and I don't really need it, so I'd be trying this just for science.

Let me know if I'm missing something here, y'all...