Multiplier is a Division Reward that helps you speed up the progress through the Divisions by multiplying your victory. Each match victory will reduce one multiplier, while defeats won't affect their balance.
The value of the Multiplier is based on your last season's performance in the Ranked Championship:

Division Semi-Pro 3 - 3x
Division Semi-Pro 2 - 4x
Division Semi-Pro 1 - 5x
Division Pro - 6x
Division Premier - 7x
Division Supreme - 8x
Division All-Star - 9x

Please keep in mind that placements below Divisions Semi-Pro 3 are not rewarded with a Multiplier the following season.