It is from the vido on YouTube, of a game character which is Ice Golem. By the context it seems it's good in defence..or defense, there were some mistakes in subtitles, because I still hear bad I was depending on them. So I think it means Ice Golem is a good unit in defensing, and he said: It shines, like a brilliant I think, on defense. But following: as a reactive meat shield, I know what is meat shield, but why as reactive? That Ice Golem, as even author said is a low unit, maybe reactive as a adjective means "the best or good in something"?