The last ability on The World Tree looks very flavorful and definitely powerful in an the all-Gods decks. But you could easily play The World Tree in any multicolor deck for its second ability only and you would have a real winner on your hands.
Fixing Mana is not an easy task and The World Tree solves this problem as soon as you ramp up to six Mana, which isn't that hard in the current standard meta. Plus, it has no legendary rule, which is another little bonus to consider.
Decks that run Genesis Ultimatum would benefit greatly from this land and those are top-tier right now.