SaltFace NS
Ultimate Mileena Exterminator
Lol ok the reasons I use U3 for my combo enders are this.
First off (if delayed wake up is not used) it leaves Mileena at the perfect spacing for a free 50/50 of MB Ball or F4. If this ender is used in the corner it goes perfectly into an armor break setup with F1,2 and if done in the corner you also have throw as a mix up as well.
Now if delayed wake up is used F3 is a perfect meaty now, you can option select with Ethereal MB Fade off of F4. If your opponent uses delayed wake up F4,4 comes out but if they don't you get F4 into MB Fade. If your opponent is in the corner & uses delayed wake up the F1 will whiff but the 2 in F1,2 will connect instead perfectly & give the same armor breaking effect.
And these are the reasons I prefer U3 as a combo ender in a lot of situations.