Move the Dead Snow marker up by 1, and spend any number of M-factor
tokens present on any single level of your character sheet. This will summon the same number of special units of that level, if they are available. Next, move your reputation marker down by the number of spent M-factor tokens, multiplied by the level of the summoned units (level 1-3). You are not required to spend all of the M-factor tokens available on the chosen level.
Rulebook page 12-13
If there is a magical reserve in the region, the dominating player also receives ONE token of M-factor. Magical reserve tokens are non-exhaustive and may never be removed from the board by any player other than Van Dyken when he absorbs it by use of The Thorn.
Acquired M-Factor tokens have to be placed immediately on the player’s character sheet on the spot labeled “0”. M-Factor from level 0 may only be used to buy special unit improvements and spent at the Raven Shadow action field.
This means that for M factor level 0 you can not buy units?