Any power- or toughness-setting effects that start to apply after Mightstone's Animation becomes attached to the artifact will overwrite this effect
Unlike Dark Confidant, Tarmogoyf backs up its reputation with a ton of high level play
And between Dominaria and War of the Spark, we have a massive number of legendary things right now
Since it makes it easier to splash various bomb rares and you get life for using them, I think it will make it easier to fight with multicolor green-based decks
It looks like overall mechanics will have us playing out of exile a lot more than we may be used to, favoring on the fly card advantage to create that classic speedy Ninja atmosphere
The utility of being able to use this as a (sorcery-speed) pump spell in addition to the fight mechanic was extremely valuable to those decks at the time, which were full of cards like Questing Beast, Lovestruck Beast, Gemrazer, Kazandu Mammoth and other beefy creatures that benefited heavily from fighting