Eventide’s reverb dev here. Here’s a few hints on tweaking H90 algs to squeeze a bit more out of your reverbs.

The thesis statement of everything I have to say is: experiment more with pre-delay and feedback.

The suggestion of Shimmer is a good one, especially with the pitch shifters set off or closer to 0 cents. Cranking delay to settings around 125-300 ms and pushing the feedback knob creates some smoother echo density build-ups. Combine this with the size setting in the lower-mid range of the knob, and you’ll find some reverbs that bloom pretty nicely.

Blackhole is another dark horse for this sort of task. Inverse gravity, size around medium, pre-delay again around 125-300 ms, feedback to taste to control how intense the echo build up is. The modulation section of blackhole is pretty powerful for the timbre, too; I like to think of these controls as depth controlling the brightness of the reverb (higher depth = darker reverb), and rate changing between subtle darkening on the lower side of the knob to seasick at the higher end of the knob. There’s more to be found in Blackhole than just galactic sized reverb.

Pro user mode is running two Blackholes into each other: the first set on the shorter side with small size and inverse gravity to soften the signal, then a second one set for your “main reverb tone”. This also works if you run the shorter Blackhole into a ModEchoVerb with the echo turned off.