I don't think Lord Vader is that ba- UNSHACKLED EMOTIONS IS LITERALLY DARTH VADER'S FORCE CRUSH ANIMATION WITH ONLY HIS HAND FACING DOWN INSTEAD OF UP.
Joke aside, as much as I don't like anecdotal complaints, LV is one of the rare cases of when these complaints are true to their nature. He is way too expensive for what he offers and he is very lackluster overall. He offers nothing that other Galactic Legends don't already give, but way better. His Ultimate is literally just a stat boost to himself followed by some empowerments to his Abilities that aren't even really worth any mention. His AoE undispellable Ability Block lasts for 1 turn on an Ability that has a 5 turn CD, same as his Ashes of the Republic duration, meaning you only make use of it once per Ultimate use. His Mastery increase is really slow and in no small part is it because "Underestimated" has a set cap they decided not to work around because they just had to tie it to his ultimate charge for some goddamn reason. Why not follow the Ability's Idea of increasing its power with consecutive uses by making it charge more % of his Ultimate with each subsequent use and remove the tie-in with Underestimated, allowing him much more freedom to balance around it.
Compare that to Jedi Master Kenobi, his ST special Ability also increases damage on subsequent uses, except its increase is more relevant, it has a 2 turn CD, a set Ultimate Charge amount and it has secondary effects that can also contribute to charging the ultimate without needing a hard cap that limits other parts of his kit in exchange for it.
Lord Vader was a cashbait for people to invest into, a rather chewed down bone for the endgame players and the top of the top whales who sit atop an 8M + GP. The way I see it, he as a galactic legend exists solely to make a difference between people who have 5 and people who have 6 Galactic Legends.
