Free: Scylla Synthesizer VST Plugin by De la Mancha

De la Mancha has released Scylla, a freeware Synthesizer VST Plugin for Windows capable of sample-playback combined with subtractive synthesis to produce a wide variety of sonic possibilities ranging from lush pads to far-out soundscapes and effects via scorching leads and chunky bass..

Scylla includes three different types of oscillators that can be modified to a wide variety of styles and three built-in samplers that can accommodate .wav audio samples, which can be played back in grain table, waveform, sample or single hit format. All the audio can be modified and modulated through LFO, volume and filter envelopes, Ring-Modulation, and Unison.

Features:

Three layers of programmable audio sources
Each layer consists of:
Sample player capable of loading full-length samples and custom waveforms
Oscillator (Dual-OSC with cross-modulation, Morphing OSC, Spectral OSC)
Each sampler features:
Playback: Oscillate, Play-Once, Loop-Release
Basic audio playback features (normalize, stereo to mono, zero-crossing)
Customizable Loop points
Granular and Wavetable playback
Loads any WAV format sample from your own library
96MB of sample content, including waveforms, samples and loops
128 presets by brian botkiller
All audio sources have independent tune, volume, and pan
Ring-Modulation per layer
Variable stage Filter per Layer
Adjustable Amp and Filter Envelopes per layer (Envelope contours can be changed)
Layer Assignable Granulator engine
2 layer assignable LFO effects for modulating ring-mod, cutoff (filter), and phase of one LF
Adjustable Global Amp Envelope
Mix level of each audio source can be adjusted
Mix level of each layer can be adjusted
Master Volume
Each audio source, envelope, ring-mod and filter can be switched off to save CPU
Midi CC support