This is what I think happens:
-Pulse field pops into existence, dealing enough damage within the field to kill a low-level Crawler.
-While the field is active, it deals a small amount of continuous damage to enemies still within the field.
-The pulses seen in the field just serve as a countdown, nothing more.
-The field collapses and deals enough damage to kill another Crawler, if one was stupid enough to wander into the pulse field.

So... at first, I thought it was shoddy design, because there's nothing that visually indicates how it works. Then I realized that I was angry about a weapon that I had to use and experiment with to understand how it works. Months ago, I was giving 343i a hard time for dropping such weapons from the game.

With this in mind, I tried using the pulse grenades more during campaign and Spartan Ops. I guess they work if you know how to use them, even if their blast radius is too small. Like every other grenade in Halo 4.

Anyhow, I noticed something interesting while going for a recent challenge. When the Catch skull is on, Promethean knights actually become interesting to play against. They're actually great grenadier units: Their accuracy is bad enough that you're rarely threatened if you're moving around, but you can't hide behind a rock and plink them to death like you can when you face Elites with concussion rifles.

They're still tedious bullet sponges, but I'd love to see future enemies that attack almost exclusively by launching pulse grenade-like munitions.

Thoughts?