Ritual tablets with more rerolls

Is there any way to increase the drop rate for Ritual tablets with extra rerolls? I used to buy them last league, but now they’re 8 divines… feels like Ritual might not even be worth it anymore.

Also, is there any mechanic where the chance for expensive Omens scales with each reroll? I’m on 4 rerolls and in ~30 maps I’ve only seen 2x Omen of Corruption. Running area lvl 80, 6-mod maps, high pack size. Ritual atlas is the usual 8 points.