Thoth gets less love than he deserves largely because it’s hard to find a really good use case for him. His damage is really not that spectacular. Hit-3 is nice, but if it gets down to just a few heroes, his hit-3 is probably only hitting one and really not doing much damage. The key value of Thoth are his minions, which are relentless hitting every turn and able to target foes hiding in the corner. A key benefit is that, unlike tile damage, those minions do jnot increase target’s mana.
I find that he is effective particularly when paired with panther. She hits first, disspelling and putting a minus purple ailment on three, and then Thoth comes in behind and wrecks their day. Unfortunately, that duo won’t kill full-health five stars, unlike a panther/Sartana duo.