"Tempered monsters" refers to creatures in a video game that have been made stronger and more difficult to defeat than their normal counterparts. Full definition
When you're going about your regular hunts, you can come across tracks and traces of Tempered Monsters which are marked in blue by your Scoutflies. (vg247.com)
When you're done with the main story assignments, there's even more post-game content to get through, including tempered monster hunts, which are reserved for only the most hardcore of hunters. (twinfinite.net)
Flash Pod effectiveness against Tempered Monsters will gradually decline after multiple uses, and will cease to have any effect at all after a certain point. (cogconnected.com)