Editing creature abilities or adding new ones.

But what if it's 1v1 in the literal sense? Then Necropolis can defeat even a Cyclops or the King of the Universe, and that's not right, that's what I'm getting at.

You probably don't know about the devastating blade of the Dungeon faction – the creature kills 1 unit + adds damage from its attack, which further enhances its deadly grip.

In general, talking about a 1v1 battle in a turn-based strategy with armies, heroes, upgrades, and artifacts is pointless.