While I personally hate Tron, and the thought of having a better version of it in the Modern format makes me recoil in horror, Tron isn't all that good in Modern at the moment, and there is plenty of hate for non-basic lands
The only reason why I chose Eye of Ugin over these two is because it has had a more significant impact on the Magic community
Firstly, its not an enchantment, so its not going to die to Mortify or Knight of Autumn or the multitude of other disenchant effects in Standard right now, all of which are going to see plenty of play with so many juicy targets for them, like Wilderness Reclamation and Experimental Frenzy
(Enter the first room or advance to the next room.)
If there's a cost associated with having Ursine Monstrosity attack the chosen player, you aren't forced to pay that cost, so it doesn't have to attack that player in that case either
How many total, unique Magic: The Gathering cards are there