That smlj song banner ish a bait. Moi didn't check probably thought special event banner should be half-priced so pull without verifying ish 50 mythrils. End up wasting 50 mythrils for a lousy SSB.
There are loads in JP which are disguised as half priced but in actual fact NOT.
At least now you know there are traps, and not pull everything when it looks great.
Like yesterday JP had 2 banners, the 5m for 3 pull FF2, and also an elemental half priced. Wah see liao half priced, and list the main 5 elements outside, wah looks nice leh. PULL! Get 1/11 crap Dorgann BSB.
Later go reddit see, it's actually a list of elemental ARMORS ONLY banner. And the list isn't very spectacular also. Knn, if check first then won't pull.
So next time when in doubt, save m!