An alternative class of easy-to-use, black-box wavefunction methods for excited states can be defined in terms of the algebraic diagrammatic construction (ADC) scheme for the polarization propagator . A first-time combination of FDET with ADC of second order [ADC ] in 2016 showed that complexation-induced shifts in dispersion-or hydrogen-bonded systems could be reproduced with good accuracy . For these calculations, a linearized embedding framework was assumed, so that interaction-energy differences between electronic states could be estimated based on integrals over the corresponding embedding potentials (assumed to be state-universal). Since apparently no monomer-expansion calculations (i.e., calculations employing only the basis functions of the respective subsystems) could be carried out, and since calculations using supersystem basis sets do not lead to computational advantages, an approximation denoted as "reassembling of the density matrix" (RADM) was introduced. Within that approach, the calculation of the density matrix for the FDE-ADC(2) calculations is only carried out using the basis functions of the active system. An extension to third order [FDE-ADC(3)] followed one year later, and confirmed the rather high accuracy that can be obtained for local excitation energies . Furthermore, this work introduced technical details of the RADM approach. Wesolowski and co-workers also conducted a more extensive test considering 351 excitation energies of 52 different embedded molecules, which confirmed the generally high accuracy for local excitations . In addition, a density-overlap-based criterion was introduced in that work, which could be correlated to errors for certain types of excitations, for which it, in turn, may serve as a diagnostic for the suitability of this methodology. Using the same test set, Hégely et al. performed a comparison of various flavors of ADC(2)-in-PBE embedding and a local domain-based ADC(2) approach.