i dont get the point of building an alexandr. like, mine was buried because i have no use for just a DEFdown with 75% probability. and... idk, buff strip for a single target. i trown him in a garbage in the first month and never actually touched him since. does he have so great multipliers?
I don't understand why you respond to a thread explaining how to build and use him, with a comment saying "why would you build and use him".
But, just to humour you -
Suppose you were talking about using him for arena instead of Warmaiden, who is a more easily attainable champ. Also, suppose you left him unbooked due to the increased cost of lego books.
Warmaiden A3 will be 100% chance for DEF down, and has a 4X multiplier. Warmaiden has 1321 base ATK and 97 base speed. Aleksander A2 will be 75% chance for DEF down, and has a 4.6X multiplier. Aleksander has 1432 base ATK and 100 base speed.
So, in exchange for a slightly lower chance to land the DEF down, you gain somewhere around 20% more damage on the attack, and about 7 more speed. That in and of itself may not be enough to justify using him - although it's pretty close, and, outside of arena, it's almost no question he'll be better.
However, the main thing he brings over Warmaiden is utility. You rarely want to run a team that has only one win condition and, if it fails, you lose. Alek will do the DEF down, but then can follow up with a pretty powerful single-target nuke (7X ATK), and also has a pretty solid A1 for CC. Both of those become even more useful outside of arena.
Now - is all of that enough to justify using him? That's something only you can answer. But I would definitely say as a dungeon wave support, he absolulely is better than Warmaiden.