Interesting topic and I have been thinking the same thing but I chose a slightly different path. :)

We all know that if you collect trophies enough, you will end up with chest full of Wolfs heads, Trolls heads and so on. (Well I don't know about you, but I do collect them all... :D ).

What if you could use those in a very Valheim way. Just like the Gods intended!

When your castle/base is under attack by a horde of bad guys, you could run to your Trophy room where you have just build your "Stone Altar of Idun". You quickly check out of the window that there are some skellys and swamp dudes out there wreaking havoc on your onion field.
- "Those bastards!" You think and you quickly grap 20 wolf heads, 10 fangs and 10 wolf furs. This is needed to Summon A Godly Beast. You ran to the altar and throw all the items on the altar.

Darkness. The red moon rises and you can feel the ground shaking under your feet. The air is filled with screaming terror as the crying of dying wolfs is echoing everywhere louder and louder - until it all stops into deadly silence which is immediately broken with unearthly howling from the distance... The beast has come.

Carefully you look outside of the window and you see a wolf - bigger than your windmill - tearing and ripping through the forest and through the army of skeletons. The summoned guardian destroys the attacking horde and and only in seconds it is all over. The massive wolf dies, decomposes and turns into pile rotten wood, bones and coal.

There's your guardian.