It's a monster set with a cool effect (exploding scamps) and somewhat unique ramping damage design, but the damage and minor timidity effect are far too weak for this to be useful with the existing cooldown of 25s. The cooldown likely needs to be closer to 12s and the damage needs to be increased. Minor timidity is far too weak of a debuff to justify such a long cooldown, and the AoE is extremely small (4m) and capped at 6 players. The marked target effect can also be cleansed, so there's also a decent chance the final and most damaging hit won't even go off.

Several content creators have made videos comparing the Baron Thirsk sets to similar monster sets like Selene, Maw of the Infernal, etc., and the damage, which is also less guaranteed, is significantly lower than comparative sets. If ZOS is concerned about Minor Timidity being abused, a viable tradeoff would be to decrease the debuff duration to 4s for example, while increasing the base damage, and decreasing the overall proc cooldown to 12s. Either way, a 25s cooldown is ridiculously long for what this set does.

Baron Thirsk is a conceptually awesome set both design-wise and from a RP perspective, so I would love for it to actually be viable in builds.

Here is the set effect for those unfamiliar: On dealing area direct damage, mark a target for 6 seconds. Every 2 seconds after, an Explosive Scamp is spawned nearby and detonates after 1 second, dealing 362 Magic damage to up to 6 enemies within 4 meters and applying Minor Timidity for 10 seconds, draining 1 Ultimate every 1.5 seconds. Each Explosive Scamp spawned deals 100% increased damage. This effect can occur once every 25 seconds and scales off the higher of your Weapon or Spell Damage.