When i play a game with a variety of enemies I don't want to feel like everyone hates me so much that they love each other. I think it would be nice to see some monsters beat up on each other for a change once in a while. It could be like Monster type A preys on Monster type B and Monster type C preys on both A and B but Monster type D doesn't care about the others unless provoked and will focus on you first all the time. I think this would make encounters more interestinfg and would lead to better strategizing. Say monster type A is giving you alot of trouble and you know Monster type C is nearby, you can lead them to each other and let them kill each other while you take a breather.
Ecosystem/Food Chain
Actually I have noticed that and also phantoms fight other monsters if they get in the way. I just want it to be more specific.
Also sometimes the giant lichen colonies fight each other.
I once saw a rocket puppy's rocket accidentally get launched into a lichen colony in an arena once. The lichen colony then proceeded to beat up on the rocket puppy. It was pretty funny to see, but I can't imagine it was doing much damage (or even any damage at all) because the rocket puppy took a beating for quite a while before we decided to step in and destroy them both.
Something to think about, I guess.
But also, if most monsters could suddenly be killed by other monsters, it would somewhat take away from the experience. It would probably be hilarious to watch in the beginning, but eventually it would probably get old...
I don't mean that monsters that hate each other spawn next to each other and they all kill each other before you get there. Monsters are usually segregated, I'm just saying that if you knew certain monsters don't get along you might be able to lead one to the other. I think it might make the world more realistic if there were feuds between other monsters instead of all the monsters against knights.
I would like it if there were a new level type that was designed specifically around two competing factions of Monsters. Final Fantasy XIII used this in a couple of places where you would encounter monsters that were fighting each other, and part of the strategy was knowing how to manipulate the fight in your favor without drawing enemy attention. Ignoring the enemy altogether meant the powerful foe would win and leave you with a difficult fight, and attacking indiscriminately would result in all the enemies targeting you and leave you with a difficult fight.
This might require a few new monster designs to do, and would probably need to be limited to a couple of special floors since implementing it everywhere would require a re-balancing of the existing monster mechanics.
Cat vs Dog
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Wolver vs Kat!
Did you know that if you trick the Lumber (big tree robot enemies) into doing its smash attack with another enemy in the area-of-effect, it'll stun the other enemies?
No real comment on your suggestion, but I just thought it would be fun for you to try if you haven't already.