The power level of the Dominus and Twilight cycles, matched with the speed boost games will get from an increased presence of poison counters, means that this set is going to have a huge impact on Commander
Unholy Annex deals 2 damage to you each turn, but if you control demons (or changelings), then it becomes a future win condition
This is especially important since the most popular partner commander is Vial Smasher the Fierce, which is also red
When you have removal sitting in your command zone that hits indestructible creatures, its hard for your opponents to feel safe committing anything to the board
But the second ability is kind of an upgrade to the Abzan Charm model of drawing two cards and paying two life for two cards (but three colored mana)
Impostor Syndrome Impostor Syndrome is the engine behind a ridiculous spiral of clone copies