|Play it first turn, just behind your front realm.|
First of all, it's the only land that you can play at any time, allowing it to be slapped down for the win if you already have 5 lands and Menzo will be your 6th. If it hits the table in this situation, it's game over. In TAV, where lands are razed a lot more easily than in standard Spellfire, this ability is even more primo.
But Menzoberranzan has a downside. Because it's so good (and so popular), everyone is running it in their deck. If you wait too long to slap it down, odds are that one of your opponents will. Once facing a Menzo on the board, your options decrease. TAV allows you to raise realms easily, but discarding them is another matter. A raised Menzo still keeps you from placing down your own (Rule of the Cosmos). So you'll need a Cataclysm, an Estate Transference, a Dissolution, or similar to rid yourself of it.
It's a catch-22: put Menzo down too soon, you'll find it destroyed or razed. Wait, and someone else will beat you to the punch.
Finding the right balance can be tricky.
It should also be noted that Menzoberranzan is one of the worst FRONT lands possible. Besides its "play at any time" goodness, it has no powers except being immune to flyers. As one of your back lands, it's passable, but the best use of this card is as a last-turn game winner - if you can play the finesse game that will allow you to slap it down!
Next time: ...the dread Lady!