Treetop Village is great when Azorius-based control decks are in the forefront of the metagame, as it gives you more plays to make when you dont want to commit any harder to the battlefield and lets you pressure planeswalkers earlier than Raging Ravine allows you to
I wouldnt recommend replacing them with tri-color tap lands
What's the worst thing that can happen if you pull the trigger on your Throttle right now
Ukkima, on the other hand, is an unblockable enabler that ALSO deals damage when it leaves the battlefield
Similarly, cards that tap for mana or bring lands back from the graveyard arent the thrust of todays article, so Crucible of Worlds and Birds of Paradise arent here
Put together, planeswalker support turns a few powerful cards into the backbone of a strategycommonly called superfriendswhere your entire deck is built around keeping planeswalkers on the battlefield and making the most out of their abilities