Urzas ability works well in Humans, as the activated ability uses strictly colorless mana, and while the ability does cost five mana, Aether Vial can be used to help pay that cost, meaning Humans has 23 mana sources to activate the ability if you count fifteen non-Ancient Ziggurat Lands, four Noble Hierarchs, and four Aether Vials
Card filtering is just a powerful thing to have access to
Now it is also a fine tool against aggro and midrange decks so much that you are pretty happy running it main in most cases
To determine the total cost of a spell, start with the mana cost or alternative cost (such as a flashforward cost) you're paying, add any cost increases, then apply any cost reductions
There are sidequests and minigames you can spend endless time on
This is one of the most broken things mono-green can be doing, and if you have been following along so far, you have plenty of mana dorks and fatties to combo this with