Predictions from our lightcone for the BPT (left panels) and MEx diagrams (right panels) as observed by the Euclid Wide and Deep surveys. For each panel we have plotted the galaxies (grey dots) and AGN (colour-coded from blue to red) corresponding to the specific redshift range, magnitude limit (in H-band) and Hα line flux limit of each survey. The surface density of galaxies and AGN in each diagram are given in the figure. See captions of Figs. 13 and 14 for further details.