Z-axis combat broken for melee - affects monsters and players - exploitable

If there is a difference in z-axis height for melee combat, players and npcs cannot strike one another, despite the animations clearly showing the weapon going through the opponent.

This is trivially reproducible. Stand on a hill and engage one another in melee combat.

This is exploitable. You can lure monsters to areas with different z-height (including things you've constructed as a player) and jump-strike them for low risk kills.

Even without exploitation, this problem is serious in areas that have a lot of hills and crags like the mountain biome. It leads to a lot of player frustration and definitely takes away from the experience of the game.

Other unity engine survival games do not seem to have this issue, so this is something unique to valheim's design/code.