This method only works once per person, but a 500% MINIMUM is a pretty nice thing i guess.
German IP ( solid one, no datacenter )
10€ on a credit card, as paysafecard, via onlinebanking
TURN OF ALL ADBLOCKERS !
Sign up via my refflink here : Cash-king
Navigate on the left bar to "Spezial-Angebote"
Click on william Hill and deposit 10€. It is important to choose "€" as a currency here. Deny any bonuses if offered
After signing up and depositing,
1. click on "my account" on the william hill dashboard.
2. click on "transfer funds" and allocate your funds from "main" to "casino" balance
Play any slot machine and spend 10€ on it.
If you really are german, you can cashout eventual winnings to your bank account and will recieve them after 4-5 days. this will require you to be 18 and to have an ID and a bank account.
Wait for it to track on cash-king. After being tracked it will become withdrawable after a MAXIMUM of 4 weeks. Cashout to your paypal. Voila we turned 10€ into 50€ within 10 minutes.
Leave a vouch please
This is a merged cashout, so it is a bit higher
UPDATE NOW ALSO HAVING EUROGRAND CASINO
THAT MEANS : SPEND 20€ GET 100€