Mage has Reverberations, a 3 mana spell that copies any minion in play and makes both copies die if they take any damage.
This already feels extremely strong as it effectively kills your important minion and gives the mage a 1 HP copy of it in play for 5 mana (Reverberations plus hero power), which is a massive swing.
When it comes to Starships though, its vastly overpowered. The mage gets a 3 mana copy of a Starship filled with deathrattle bonuses their opponent has been building for the entire game. Every mage deck will effectively also be the strongest Starship deck just by including 2 copies of a three mana spell, on top of their own gameplan.
I’m not sure how I’d fix this without ruining the card, but I’m saying right now it will need to be fixed.