This is a pretty unusual type of bonus, but it's one that can pay off big time if you have a large bankroll and are willing to shoulder a little risk. It’s only 30%, but its available on deposits right the way up to £1,000. From the moment you make your deposit, your wagering begins being counted, then the moment you hit a figure of 20 x your deposited sum, they will drop a 30% cash bonus in your account with no restrictions, no wagering requirements, no B*ll S**t – now you’ll have to do your own calculations as to how possible it might be on your favourite game to wager say, £1,000 twenty times without dropping too much below the £700 required to end up in a profit, but its certainly possible – a twenty times wagering requirement wouldn’t be too much to ask on a standard type of bonus these days, so its worth giving this some consideration I would say.
I searched through the terms and conditions, and from what I can see your play whilst under this promotion is not limited to the games in the “Bonus Games” tab only, and I don’t see a contributions table either, therefore, its possible you could maybe grind this on roulette, blackjack, or video poker without breaking the rules, although I would probably check this with support before committing to £20,000 of wagering!
On the downside, you have to wonder why they prefer this style of bonus? I can think of one reason, which is that if you are exceptionally unlucky, especially if you do decide to make the big £1,000 deposit, it's possible/probable you might decide to continue depositing until you meet the 20 x requirement – which has to be done within, I believe 7 or 14 days – in order to make sure you do eventually receive your bonus. Of course this bonus could end up being a poor compensation for all the deposits you make up to that point if you are extremely unlucky, so be careful, remember when to cut your losses, play safe and all that kind of thing :)