aircombo > S Pin > 236H
This setup can be looped easily in the corner by backdashing after 236H to crouch and pick up the Pin again. Meaty disc will hit opponents trying to mash/jump out on wakeup, allowing Millia to avoid wakeup reversals and Blitz. The most common mixup to do here is jump, FD until the crest of the jump to block reversals, and late airdash high (j.PH or j.KS) or land low (2K). Usually this pushes them too far for 2H, ending in a 2D knockdown on hit midscreen. In the corner she can confirm with c.S > H to loop the mixup.
Meaty disc also allows Millia to use the disc hit itself as a mixup by crossing up. The safest way to do this is superjump forward, (delay) air dash back, (delay) air dash forward. The superjump puts her out of range of most reversals and varying the timing on the air dash back is what chooses which side the disc hits. The air dash forward timing can be adjusted to help pick up for a combo afterwards. Common conversions are j.H > S Pin, very low j.H > 5K > air combo (midscreen), and j.D > land > air combo (corner). Alternative ways to cross up with meaty disc are IAD, Roll, and Turbo Fall, which can be easier to convert off of but lose to common reversal options (Blitz, DP, Throw).