The Returning User Reward or the WIll of Fire requires you to reach Lv30 or Lv35 first to be eligible to have this kind of Returning Rewards .. Your Account must be offline for minimum of 7 days to trigger the said Rewards .. The Rewards (Exp and Cps) are determined by your level, the rewards varies for each level bracket .. And from what i've heard from other people, this Rewards has a cap of 1 month ..

I'm level 88,any idea what the rewards could be? I think a friend told me that she had 1400 coupons after returning.

Also, is the exp gonna be enough to level me up? I'm trying to stay under level 90 to farm sage and I don't want to go to level 90 without at least having 90-100k power.

You can try for rng event ninja, usually it drops alot easier if you afk for month or two.

I have no idea how much coupons you can earn for a month, but one of my account (lv83) was offline for a week and got 800+ cps when i opened it back .. The exp gain was around dunno the numbers but my char was lv82 that time with 80% exp, after getting will of fire, i ended up leveling up to lv83 with 28%ish exp ..

After being offline on 1 account for a month or so. (I only log it to help pass missions around to people) I got around 1,100 coupons at 86 or so.