Does anyone else really want Tarquin to get absolutely bashed in?

[Clistenes]

A small correction: what Tarquin does is sign up to be a subordinate and adviser to a pre-handpicked patsy. If Tarquin sees Xykon in this light he's setting himself up for a fall, just like everyone else who's underestimated Xykon.

This.

Sadly, I doubt Tarquin is going to commit that mistake; he's to careful ans savvy.

I think Tarquin plans will break apart because of Malack, when the latter discover what is really going on with the Gates (I doubt he would like the idea of a SOUL destroying weapon that could threat his own god being put in the hands of either the Dark One or mere mortals, Tarquin included).

The other blind spot of Tarquin is Elan, which he considers a leader and talented adventurer despite all evidence. If Tarquin makes plans counting on Elan being smart, he is screwed.

And of course, Xykon could kill and turn Tarquin into a Death Knight outright upon meeting him, without allowing Tarq any time to appraising what he's getting himself into.

I personally think Tarquin is too genre-savvy to try to use the Snarl once he learns about it. The Snarl is one of those things that always screws the flamboyant cackling villains he despises.