Deathmark for 2 turns sounds pretty OP but it would be fun to have this ship in the game. Based on Star Wars Rebels, it should be fast, have shields, and a lot of firepower. But that's to say it has shields isn't to say it should be tanky - it's a huge ship that should be really easy to hit so perhaps it ought to be squishy in the same way the TIE Adv X1 is.
It might be nice to see some direct synergy with TFP, as we see the Defender flanked by TIE's (likewise for TIE Adv X1 for that matter)