Executioner is a Magic affinity rare from the Knight Revenant faction. Executioner has abilities that scale from atk and def therefore people find him difficult to build. He has decrease turn meter and stun that both require accuracy to activate and he has an increased defence and self counter attack, a great ability for early game arena.
When Raid was released Executioner was the champion to build! He was strong and was a fantastic campaign farmer. Executioner did take a small nerf and is nowhere near the man he was. Now a mid-tier rare capable of supporting teams and annoying to fight in early game arena.
His best use is Faction Wars due to his decrease speed and turn meter control.
He does well in the magic rare secret room as he just is a bit of a beast of a rare, his a2 is an AOE Decrease SPD.