The Flare tool combines the Push tool with a Linear falloff. With this tool, you can quickly flare out a specific portion of the mesh with the Linear falloff as the modulator.
Push—
Distance: Defines the actual amount Modo moves each vertex away from its original position. Modo moves the vertex directly along its normal. This value can be positive or negative.
Linear Falloff—
Start X/Y/Z: Sets a 3D position for the beginning of the Linear falloff. At this position Modo sets the falloff value to 0. All vertices at this side of the falloff receive no effect from the tool.
End X/Y/Z: Sets a 3D position for the end of the Linear falloff. At this position, Modo sets the falloff value to 100. All vertices at this side of the falloff are affected 100% by the tool.
Auto Size: Snaps the Linear falloff to the specified axis and scales it to match the selected geometry.
Reverse: Swaps the Start and End values to flip the falloff.