All - simple question. The TWS KGB Agent bystander token offers prob control for 15 points. However, the prob control is contained in a "Horde" Power. The power itself does not indicate multiple tokens are needed to use the power. The text is as follows:

HORDE: EXPENDABLE RESOURCES: KGB Agent can use Probability Control, but only for friendly characters' attacks. When he does, you may remove 1 KGB Agent from this stack and modify the final attack total by +1.

So the question I have is can I have only one KGB Agent and still use the probability control (a mere cost of 15 points) or would I have to have multiple tokens in a stack (minimum cost 30 points)? Thanks in advance for your time.

Directly from the rulebook:

"HORDE TOKENS
Horde tokens are bystander tokens marked with the "horde" symbol. Unlike other characters, identical horde tokens (those with the same set symbol and collector number) can share a single square on the battlefield by being stacked, and when stacked they can use special powers called horde powers. Many horde powers scale with the number of tokens in the stack."

If you're not stacked, you can't use Horde powers at all

I understand where you are coming from, however imho you can have a stack of 1.

No, you cannot. From just a few lines further down in the same rulebook:

"STACKING AND UNSTACKING HORDE TOKENS
Two or more identical friendly horde tokens in the same square after actions resolve is a stack."

FWIW, Melkhor is right... a "stack of 1" is not a stack, it's a Bystander.