Never met a boar, never in all the games I have run...it's true that I never look for it so deep, but never even for mistake? Where are they?
once i fegularry hunted for them (with my rangers) and got even a collection of 30 skulls or so (maybe i remember it wrong but many, hunting for boars was a way to rise strength to +99 or so, I dont remember exactly as it was in V15 in more than 10 years ago
Boears are common just move thru wilderness in level like 30 exp or higher,
to mace hunt of them one should be preferably cursed or doomed (i dont remember) then encounters are much frequent,m but anyway they are just
quite common wildernes snoop arounders
Giant boars start to appear as a forest encounter from level 15 onwards.
From level 25 onwards a big group of additional possible encounters is added, so it is advisable to get the skull before level 25.
Since forest is the terrain that produces the least encounters, it MAY be advisable to increase the chance of encounters by being cursed or doomed and thus save game time. If you know what you're doing that is.
A good time to get the skull is thus right after eating the oracle, when you're on your way to the next altar to clear cursing and dooming. Just keep looking on forest squares and stay clear of roads (lone necromancer->ghuls->doomed characters don't want that).
Oh, and as for the original topic: For an ultra ending Mindcrafters are very rewarding, because with a normal ending you don't get much opportunity to use the Greater Telekinetic Blast when you finally get it. With an ultra ending this is so much different, and you feel more rewarded for the early game struggle you had to face.
The boar skull is actually classified as a tool, or at least that is the item category it belongs to.
"Hell is empty and all the devils are here."