I’m wondering if I should put it into my build now if it’s going to be necessary later.
No, all specializations get another movement ability. In addition nearly every boss attack is telegraphed and can be dodged just by moving.
Big boss attacks are usually pretty slow and you can just dodge manually. Transplant does make it easier.
Warlock gets Profane Veil, which is sort of like a movement ability (they can go invulnerable and walk somewhere). Is that what you mean? I can’t find any similar abilities for Lich or Necromancer. What do they get?
Profane Veil by default is more a defensive skill and no traversal skill.
You can spec it into being a traversal skill though.
Not every mastery has its own traversal skill, but all base classes have at least one.
Are they required? No
Are they really good and useful and often can give otehr benefits and utility? Yes
If you actively decide to not use a traversal skill you defintiely want to make extra sure that you have as much movement speed as possible. High unconditional movement speed is very important and high uptime on Haste will make it even better.
Lich gets a dash from Reaper Form while transformed.
Skeleton Mage can be upgraded to be a teleport, which is available to any Mastery.
Skeleton Mage is a Necromancer ability.
Skeleton Mage is available to every Mastery.
Up until the 25 points threshold skills (and passive trees) are available to all masteries of that class.
If you have a skill slot to spare, I would put an unspecialized transplant in the slot. There are skills where you only need to use them when they are proc-ed so you could end up with a spare skill slot.
It’s not required, but it makes dodging some mechanics much easier.
You can also convert chthonic fissure to become a traversal skill. So that’s another option.
Profane veil won’t stop you from dying, fyi. You dodge attacks, but DoT attacks like Lagon’s breath will still kill you.
Required no, make it a million times easier? Yes. The rogue movement skill and sentinel are some of the best which full out make you invincible during them. I can meme mechanics like i am asleep. Nothing like dashing through instant one shots
Transplant is really nice. You don’t have to spec into it, but whether or not you do depends on the rest of your build.
Personally i would say specializing into a traversal skill is never neccessary but having it in the hotbar probably is. I personally couldnt foresee doing Ch8 and Ch9 without a traversal skill at the very list sitting ont he hotbar. Specialization is only if you want to integrate specific functionality into your build.