It'd suck if it was just for MDIs. They could always just give the (some, if not all, to be greedy) challenge mode rewards for appropriate mythic+ feats:all 5s-title, all 10s mount, all 15s teleports.
ive gotten 3 diff. types of these in my bags so far, yes they are neat saves the 5-6 flight time from one end of map to other, just not sure how to get them and mine have charges so when its gone it gone. not like u can go round the corner and buy another one.