Flanger is a mix of original and delayed sound, while the amount of delay is variable in time, relusting into a sweeping effect. It is mostly used on clean guitars, short parts of basslines (even bass guitars in metal), drumloops and all kinds of synths.

WetDryMix: A delayed/original sound rate controls the presence of flanger in the sound. And because flanger is an interaction between those two, maximum is achieved when the WetDryMix is set to 50%.

WaveShape: Sets the delay variation envelope. 0 is linear change and 1 sine.

Frequency: This is period of the Wave Shape repetition.

Depth: Controls the maximum delay additionally added by the WaveShape oscillator to the original Delay parameter (see below) and is expressed in % of Delay.

Phase: This determines posistion of left and right flanger on the LFO = low frequency oscillator = WaveShape. Phases 0 and 4 set the channel difference to period/2, phases 1 and 3 to period/4 and finally phase 2 to zero.

Feedback: Picks the flanger output and sends it back to the input, which results into a metallic effect, easily audible at higher feedback settings. Lower values add bright and higher dark resonance.

Delay: Fundamental delay of the "wet" sound.

Setting examples:

Synth flanger

WetDryMix: 40
WaveShape: 0
Frequency: 0.90 hz
Depth: 100
Phase: 2
Feedback: -40
Delay: 3.1

Makes synths more fat and is good to chain with Synth chorus. Changing the Delay parameter value can very nicely modulate the sound and it's worth to be adjusted with midi macros in the track.

Guitar flanger

WetDryMix: 40
WaveShape: 0 or 1 (1 produces more panning effects)
Frequency: 0.25 hz
Depth: 100
Phase: everything but 2
Feedback: -40
Delay: 2.4

It can make some guitars sound really beautiful.