@JeremyECrawford Slow spell wording confusing. Written as saving throws initially & once more than spell lasts for duration.

— Carmine (@nirvanstryder) September 25, 2015

You make a save vs. the spell. Fail: you're slowed till the caster's concentration ends or your later save succeeds. https://t.co/xLIJ4E7XHL

— Jeremy Crawford (@JeremyECrawford) September 25, 2015

@nirvanstryder“Later save” as in one more save than slowed until end of spell’s duration or make saving throw at end of each turn?
The slowed target makes a saving throw at the end of each of its turns.

— Jeremy Crawford (@JeremyECrawford) October 6, 2015