Giant-amplitude variability of radio-quiet and radio-loud AGN: probing an extreme accretion regime

The extremes of variability offer valuable new insights into the drivers and physics of AGN. Here, we present the most recent results from our ongoing long-term timing and MWL spectroscopy cam paigns on some of the most highly variable, best-studied AGN known to date, including transient AGN like IC 3599 and other changing-look AGN, and exceptional blazar outbursts like that of 1ES 1959+650 discovered by SVOM and followed up with Swift. Results are used to gain insights into the underlying variability mechanisms including accretion disk and BLR physics. Notable differences are seen in the optical spectral response to giant outbursts, implying different intrinsic mechanisms at work