As a heavy weapons jax main myself, I would say #1 thing to master in this matchup is your punish. If you're not getting max damage for her mistakes, you're letting her get away with murder. You have to let Milena hang herself, then make her hurt for taking those risks. One mistake from Milena, you can full combo punish her for 35%+ and you're sitting pretty in the corner (where jax is an absolute monster). Also on wakeup, just stand block. Milena players love to roll and ex roll on wakeup. Block it once and punish hard and I promise you, you will make them rethink waking up ever again. Especially in the corner where they will eat 50%. Then, once they're shared to wake up, 50/50 or pressure the shit out of her. If you're being out zoned, just block everything patiently. Let her have her little chip damage, what is she gonna do once you've made your way in? Jump at you? D2 or ex grab. Up close jax dismantles her. Patience is a big key point in this matchup. Also, practice punishes for things like her teleport. You can block teleport and neutral duck and wait for the sai (if she chooses to throw it to throw you off) then punish with something like standing 1, 11, run cancle 11, f212, d3+4. Last thing lol, if you play heavy weapons jax, then trade bazooka with sai all day long, the trade is heavily in your favor (but be careful for yolo teleports after they catch on). You'll be fine dude, all matchups no matter how good or bad just need practice.
. Be sure to abuse her weak low pokes and general slowness as well. Check out as much of her frame data as possible too, see what your options are in various common situations.
