Where offers 30%?

SD was paying (and charging) after each bet, but they changed it so now they pay only at the end of each month I think.

The way it works is you get 10% of the action of all the players you refer. If they lose, you get 10% of their losses but if they win you lose 10% of their profits.

I tested it out by referring myself and winning a bet, and my main account's balance went negative by 10% of the amount the new account won.

They say they're not going to come after you for negative balances, but that they're not going to allow people to abuse the system.

I pointed out that I could make a new affiliate account for each person I refer, and just throw away all the ones that refer winning players and keep the ones with losing players. That's probably considered "abuse", but I don't know how they would be able to tell if I registered each one from a different IP address and such like. Note also that by referring yourself you can make a +EV bet: if you win, you pay 1.9% house edge and if you lose you get 10% back in your affil account. That's a +3.1% EV if you bet at 2x, and higher if you bet at higher multipliers, up to around +8.1% for the highest multipliers.