Everything’s already been said, but I can’t resist piling on for emphasis. Elemental debuff is powerful, but also very rare and therefore even more valuable. What’s great here is that Falcon and Jackal are four stars, which make them more accessible. And they are the only ones who do it for their element (same for Panther, but she is way less accessible). That means they’re hugely valuable for titans, wars, raids, and the map (so basically every phase of the game).
Panther is widely regarded as one of the best / most valuable heroes in the game. I feel it’s less common now, but two Panthers flanking Guin used to be a fairly common defense.
Falcon make Kashhrek a joke of a tank and is a major inflection point between Kash being very annoying and very easy.
Jackal is very fast (also a rare attribute). I got him on my only pulls this month (a 10 pull) and am ecstatic! He’ll really help me against Kunchen, as his skill counter Kunchen’s special really well (since there’s no way to lower Kunchen’s non-elemental defense). ALSO, he’s a rogue, which for me is also huge. I have a pile of Rogue emblems and none used so far (others are Scarlett and Danzaburo).