The ability to force stuff to block him is kind of silly, because in the late game its pretty likely your opponent can block him with a couple of 2/2s or something
In general, when looking at power level, I considered the overall game plan, the synergy of the 99 with that game plan, things like interaction, ramp, mana base and card draw, the commander, and the power of the remaining stand-alone cards
Cards like this have inherent flexibility in that they cover two slots on your curve and also mitigate the drawback of being legendary by being two different cards in one
With so many strong cantrips for one mana, as well as a mana curve that stops at two, the mana requirements for this deck were even lower
The mix of orcs, goblins, and humans also fits nicely with how the army of Sauron was in the books