Thank you for your comment. Though I don't speak spanish, I got a rough understanding through internet translation.
It's true that there are only a few non-basics. Mainly because Yawgmoth needs black mana to function. Also because I haven't included all non-basics yet, only a rough shell that came to my mind when building the deck first.
Also I use
Urborg, because I had it laying around and it always helps
Cabal Coffers and
Crypt Ghast to give me more mana. 1-3 more mana can be crucial in some situations and outweigh the advantage I give my opponents (if any).
Then I could always put in a
Sheoldred, Whispering One - would that justify
Urborg more?
At last, I mean, it's Yawgmoth's Tomb - so definitely on flavour