Blindside Attacks don't combo?

[Zetsumei_Tsunarashi]

In order to perform a combo, you have to use the skill from the direction it says in the skill's description. The only skill lancer has that combos from behind is vorpal thrust. If you try using blindside on any other skill, it's not going to combo.

That said, it would be silly to use blindside with vorpal thrust since the combo bonus is increased crit rate. It's better to use blindside on something that a.) doesn't have a naturally high crit rating, b.) is a single hit WS, since blindside only effects the first hit of a multi-hit WS and c.) is at the end of a combo so the direction doesn't matter. By process of elimination, that leaves you with doomspike.