It's registered in a massive 14% of Green decks and 169,313 decks over at EDHREC.com
However, while Ruric Thar is heavily dependent on the spells being cast by your opponents to be of specific types, Omnath's ability is based off of the cards that you cast, putting its triggers entirely within your control
Combine this with the fact that Burn decks really only do one thing (throw burn spells at their opponent's face), and you have a scenario where any card that incidentally gains two or more life ends up being the equivalent of a Time Walk against burn
(10/4/2004) In multiplayer games, you can choose a different opposing player each time it the ability is activated
Fast lands tend to be great filler lands to bolster an otherwise fetch land-centric mana base, especially for more aggressive decks
2 graveyard recursion higher budgets I recommend more tutors 2 flexible tutors