The Oathbound Paladin has always had issues since it’s release and a user-submitted video shows how broken it is in PVE. The class probably need a full balancing pass and the devs know, because most issues have already been reported back on the public test shard.
What you can see are two major broken mechanics: The first is the combination of Prism and Burning Guidance producing insane amounts of DPS. Prism was an early concern when the class hit preview for the first time and they actually did fix some damage loops involving the skill and Burning Guidance, but Prism can still proc off each other when used with a second Paladin. With the current state of AP generation it’s easy to spam dailies and have Prism up at any given time, meaning both Paladins heal each other back and forth and since Burning Guidance procs uncapped, they produce huge damage loops that burn mobs and bosses in no time.
The second issue centers around Shield of Faith. The daily stacks multiplicative and provides a separate layer of DR mitigation, effectively ignoring the DR limit of 80%. Two Paladins provide a massive 75% damage reduction to all damage that has already been mitigated by other sources (normal DR etc.). Add a DC and a GF with Knight’s Valor and your group will be virtually immortal. The remaining damage is so low that you can even go immune if you add powers that absorb flat amounts of damage like Empowered Astral Shield or the Cold Shoulder boon.
With the right group setup, you can rush through any content and it’s safe to say the Paladin is indeed mandatory right now. In the early stages of the game, we had full GF parties for a short time due to a bug and now full OP parties are possible as well. The proc-fest of Burning Guidance melts any opposition and Shield of Faith mitigates any damage to 3.125% after normal DR, meaning that even millions of damage from dragons would suddenly turn into a scratch.