If you don't know dEUS, you need to hear "Selected Songs", the celebration of their 20th anniversary.
The second option is a far more pleasant one: buy the seven albums that dEUS has released the last 20 years. You won't just be able to listen to the tracks that made it to this compilation, but lots and lots more.
The final option combines the two previous ones. You already have the seven dEUS albums, and you still think that you need to hear this compilation. Well, good for you. According to my psychiatrist there's nothing wrong with that. It's a bit weird (and I'm paraphrasing here) but not harmful.