Phantom Assassin is the embodiment of hero killing in Artifact. In a game where heroes are the focal point, an 'anti-hero' card should be pretty good right? Well it is. Absurdly powerful in combat and a signature card which unconditionally KILLS an opposing hero will have PA seeing play for years to come.
With Efficient Killer in effect, PA has the second highest modified attack of 10 against heroes in the game, only lower than Bounty Hunter with Jinada (11), which is only on 50% of the time!
8 Health amazing for a black hero, only behind Lich's 9. Overall, Phantom Assassin has some great stats and can cross-kill every hero in the game save for ONE - Bristleback.
This brings up PA's attack to 10. Ten! That means you can one-shot around 70% of heroes currently implemented in Artifact. If you cannot distill a meaning from that, I'll just say its 'good'.
There's nothing fancy here. Efficient Killer is simply that - allows Phantom Assassin to be an extremely efficient killing machine.
The only note I can put here is that Efficient Killer is 'lumped into' her attack in combat and not a separate instance of damage.
First and foremost, it's pronounced 'ku də ɡɹɑs'm or koo deh grahs. Lul.
Extremely powerful. No amount of enemy defense can overcome 'Condemn a Hero'. I don't think I need to go over how relevant this card is in a card game revolving around heroes They are on average the strongest units and allow the casting of spells.
More on that note, Coup de Grace's spellcasting disruption effect should not be ignored. It may not always be right killing off your opponents fattest guy when instead you can use it as a pre-emptive 'silence'. A two turn silence even!
It has a downside, wherein you discard a random card. There are a ton of ways to mitigate this. If you have more bad cards than good cards in hand, you will likely get a better result and vice versa. RNG is RNG and this is a WELCOME price to pay for Coup de Grace's effect.
Lastly, you can also Condemn your own hero with this for a very expensive and very desperate 'Town Portal Scroll' effect.
Phantom Assassin is powerful enough in combat to merit a spot in any deck wanting black. Coup de Grace also gives you hard removal for heroes which is very rare. It's safe to say PA is a prime consideration for any deck running black. She of course fits into any deck that aims to kill heroes, if that ain't obvious by now.