Is it possible to get a +5 to raise skeleton on a shrunken head, I’ve heard about upgrading a crude elite white head in the cube to reduce it ilvl then charsi imbue it with a low level character then rerolling it with 6 perfect skulls until you get the right affixes. Does this sound possible??

get a level 1 char with a super high qLvl white base (Succubus Head/Bloodlord Skull iirc?), and I believe you can hit +2 Nec / 3 Skel.
same janky ass method as some weird ass high qLvl sin claws i assume

+4 is possible, has to be <ilvl 24 (+1 summoning, +3 raise skeles)
>25 literally cannot have +3 raise skele on it, therefore no +2 summoning, no +1 necro, no +2 necro