Shuriken has released SqakAttack, a free MIDI-controlled buffersynth with a duck for GUI.

From the author:

A one-trick pony if I ever saw one, this here is SqakAttack. Feed it audio and midi, AND when a
midi note is played it will do buffer synth magic on the audio you fed it. There is also an automatable parameter that you can use to adjust the pass through volume. Have a look at the youtube instructions for a better explanation.

So… just give it a try!

Visit Shuriken for more information and a link to download SqakAttack.