LANDING: Once per game, as a free action you may have Ziran the Tester gain the "boot" symbol for the rest of the game. When you do, Ziran may use Quake as a free action to target all opposing characters that can't use the Flight ability.

To use this version of Quake does Ziran need to be in adjacency? The power makes it sound like he can use Quake against all figures that can't use the Flight ability, regardless of adjacency.

Quake makes a close combat attack targetting all adjacent opposwing figures. The Flight is the stipulation, not the adjacenecy. Powers that do would specify (regardless of adjacency, for example). Without the specification or errata, it does exactly what the special power and PAC says it does.

Due to the odd wording of the power, we have been playing it exactly as its worded;
"Ziran may use Quake as a free action to target all opposing characters that can't use the Flight ability."

While normal Quake itself only effects adjacent targets, there have been several variations of special powers that increase the range.

I'm sure it will be cleared up in an Erata. My thoughts are that if it wans't intended to be this way, for one, they would have just given him a click of normal Quake, and two, it would not be limited to a once per game ability that also costs you the use fo flight for the rest of the game. Kind of a hefty cost for a simple power that some >60pt figures have without the restrictions or cost.

The "all" takes care of that pesky adjacency issue and, well, targets every figure who can't use Flight, regardless of adjacency.

This was my assumption as well because of "all".