Archon of Valor's Reach - 4GW
Creature - Archon (Rare)
Flying, vigilance, trample
As Archon of Valor's Reach enters the battlefield, choose artifact, enchantment, instant, sorcery, or planeswalker.
Players can't cast spells of the chosen type.
Brian Kelly, your God has arrived.
Evaluating this as an Oath creature, the important thing to note is that it isn't a "come from behind" target, but is pretty powerful as a "cement a lead" target. Think Gisela, Blade of Goldnight, which is often played in Oath as a way of making sure you don't lose to a Walking Ballista off the top.
Additionally, this functions as a Iona, Shield of Emeria that is easier to cast in many circumstances. Naming sorcery against DPS is similar to naming black with Iona. Naming artifact against Paradoxical Outcome still stops the combo since it involves recasting all those artifacts that have been returned. The fact that is stops casting altogether means that players can't trigger Monastery Mentor like they might if this were a Chalice of the Void instead.
Finally, for those that might miss it, the effect is symmetrical.
There are many other lines and considerations to add for this card, but I'll leave it at that. What does everyone think?