YMMV, of course, but here’s what I’ve found.
Jackal and Joon are absolutely LETHAL together. I have Joon to tier 3 and Jackal maxed at tier 3. I’m actually afraid of what will happen when I get my 4th orb of magic.
But I digress.
Using Joon and Jackal together in raids is amazing because of their fast mana. They charge up at virtually the same time, needing 8 and 9 gems (I believe, correct me if this is wrong). Hitting ANY hero with Jackal first and then Joon is an automatic out. A Yellow diamond means 2 down with minimal return fire. Now, I’m not telling you all how to assemble your teams, but those of you using 3 healers, think about what I just said.
Jackal is soft on D though. He’s a frontrunner for sure.
Using them for titans is spectacular as well. Jackal charges so fast and keeps the -54% debuff going while Joon blinds the titan. If I get a yellow diamond he’s in for a world of hurt. The last time I had the Purple Dread Dragon (6*) I dropped 51k on him.
Falcon
I use Falcon and Scarlett the same way I use J and J, but against greens of course. They’re also very effective against higher level events. I used them to finish the last event in the advanced stages because Jackal was just too soft. The spread fire really weakens the side. Falcon is stronger on D and health, softer on Offense but he’s more of a setup man and Scarlett’s the finisher anyway. She’s the glass cannon. Together they’re deadly.
I also use F and S to go after stronger raid teams. I win as many as I lose.
If you have a chance to level them up, do it. They are amazingly fun and effective.