The omen effect from killing a single Illager captain (from a patrol) is enough to, when inside a village, summon all raid waves, including the one with the evoker. Happened twice already. I'm used to playing in Java, and there you only get up to two waves per one kill.

I used to have a very high omen level before but got rid of it by drinking milk. I'm new to bedrock and don't know how to check the description of the status effect, so I can't confirm the exact level of the omen effect I'm getting from a single captain.