These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Warlords Battlecry
Demonic Spiders: Units with the assasination trait, which gives them a chance to One-Hit Kill anything that isn't a titan or a building, including your hero.
The Plaguelords in III are incredibly overpowered, have access to cheap hordes of units and very powerful area-of-effect monsters. Their only downside is a lack of ranged units.
In the first two games, a character who was created for the campaign mode could not take part in skirmishes (and receive experience for it) until they finished said mode and exported their user data. In the third game, these two modes were integrated, meaning skirmish matches could be played independently using the same campaign hero. A savvy player could set up matches against ridiculously-hard AI opponents who had little to no resources, then reap hundreds of XP points in a short time. By combining this with a few upgrade points pumped into the the Knight Lord skill for the Knight class, a player could conceivably start a campaign mode tens of levels higher than the initial difficulty, and (by spending all starting XP on Knights) have a posse of bodyguards who will ravage anything and everything in their way. The campaign becomes trivial as a result of this, even on the highest difficulty.
Most Annoying Sound: The warning sound (a steadily-rising heartbeat) as the player nears death.