I think its in 2 weeks. It's only once a month (lasts for a week).

Not 2 ..would be three weeks more..since last rebate was last week....normal gap between refine rebates is 1 month..so expect it at the end of november

In 3 weeks.

I'd suggest if you didn't collect 500 for whatever runes you need. Skip and do it next rebate.

Pill will come handy in late game. You will need it.

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Also with charm rebate, try to get 100 boxes for rainbow. I usually did once every 2 months. I could only get roughly 50 boxes ish per month from participate all events and not buying.

Do big power jump better than small jump and missing out big prizes.