UPDATE: No RNG after all! - Idle Heroes 2024-04-26

Now that the event has gone live, it seems I was wrong here, and the randomness just doesn't exist. You don't need 200 of a single item to do a rite, you can mix and match.
So basically, the event is a lot better than I thought.
English spoilers: sites.google.com/view/1ciyeri...
Chinese spoilers: mp.weixin.qq.com/s?__biz=MzI5...
My event scratchpad file: docs.google.com/spreadsheets/...
The Barry Gaming video I discussed: • Idle Heroes - Low Spen...

[@Alsadius]

CORRECTION: The event does not work like I thought - you don't need 200 of a single item, you can mix and match. So this event is way better than I had predicted. Also, because of a technical glitch, there's now an extra reward at the 4th tier, of 1M stellar, 1M crystals, and 30 train tickets. This is a pretty substantial bonus, so getting to the 4th tier (which was already a pretty good stopping point) has now become much more desirable. I'd probably stretch to get there, if you were on the fence before.