Which units would you like to replace or add?

maybe karate? Or even better, permanent magic? Let it cast spells all the time (whether it's a Titan or a Colossus). Or let the Titans kick, and when they become Colossi, they get permanent magic.

No, if a Titan is going to do karate, then the units should fly across the entire battlefield, but otherwise, magic is good, but then we probably need to remove the lightning strike, and also figure out what magic to choose so that it is useful and there is still balance, or maybe give it the ability: anti-rune, i.e., against dwarves, so that they don't mess around with runes. There will be a chance that the unit that used the rune will receive an anti-rune effect, i.e., instead of a resurrection rune, a disintegration effect will be cast, and so on.