The issue I have with Hickman with regards to his X-Men output...is that there were just too many chef's in the kitchen at the same time doing their...
Mercury was probably resurrected off-screen at some point, given how Onslaught attached to people who were resurrected to manipulate them, and we saw...
Well...technically it's only 14 mutants going by what Hickman stipulated (13 if we count the F4 kid as no longer a mutant) with one or two mentioned...