A multifunction valve includes a valve body defining an inlet, and outlet and an interior chamber. A flow control gate may be disposed within the interior chamber and comprises one or more protrusions configured to provide a high level of precision control of a fluid flow rate through the multifunction valve as the flow control gate is rotated through an arcuate range of positions. The protrusions may comprise a cut-out portion, wherein the size and/or shape of the cut-out may be configured to modify the fluid flow rate through the multifunction valve. A method of modulating a fluid flow rate includes directing fluid flow through a multifunction valve from an inlet to an outlet, the multifunction valve including a flow control gate, adjusting the flow rate through the multifunction valve by rotating a control shaft to position the flow control gate to variably occlude the outlet of the multifunction valve.