Any promos which is based on wager will be suitable for those who have higher bankroll but it wont be suitable for us with smaller bankroll
Users can wager easily with dice or similar games that have low HE. Slots player is at a disadvantage if the platform provides dice, etc. Yeah, I know there is only dice duel on Duelbits so it might not be applicable. My point is if the promotion is aimed to increase slot players, it would be best to tailor the promotion to fit the theme.
Slots = multiplier, big win
This is the area where other big platforms seem didn't care as they put dice (the wagering machine) next to slots (the rekt machine), and use wager to rank up, as competition, get profit-sharing tokens, etc.
If duelbits is going to have another raffle like the one they did on Christmas, I think they can just do the same where players can claim tickets every single day. Requirements can be the same as well, players who made deposit at least $xx in the last 7 days can claim the free tickets. Frankly speaking, I would like to see different requirement, because the previous requirement was easy to be abused by multiple accounts. So I think roycilik's suggestion is good enough (based on wager)
Exactly what I've suggested (minus everything related to wagering), the win multiplier (instead of the wager) acts as a cheater prevention mechanism.