It's very strong with other cards that want to know the top of your library, or with library manipulation like in color Sylvan Library or Sensei's Divining Top
Now, cards are organized into groups of their first color, so the total numbers are changing
4 Omnath, Locus Of Rage A Gruul (green/red) Elemental option, Omnath, Locus Of Rage allows each land you play to offer Elemental-based value while serving as a flexible removal engine
It's a shame that the card itself merely generates a measly 1-2 mana to pay for your cumulative upkeep cards, which isn't going to matter much within a couple of turns
Why do the lands enter the battlefield untapped
Not only do you discard the two best spells from your opponents hand, but they also need to find a way to kill this creature, potentially drawing removal out of them, if they find it at all