[Suggestion] How to make monster battles challenging and enjoyable.

Introduction

The monsters look really good: nice variety, unique, good animations.

But let's be honest, the tactical battles are dull and repetitive. It's always "bash the monsters to a pulp in melee combat" for me. I never had to intelligently design a specialized army to fight a monster. And although monsters use their skills at the beginning of battle, they are quite ineffective, and ignorable, and the battles always end in a melee brawl.

To me, most battles with monsters  should be unique, and that means the way I approach the battle, the strategies I call upon, are different for each monster type. In other words, each monster offers a new challenge.

So how does one make monsters more interesting?

Quick Summary:

- Add physical damage immunities.
- A given monster type should exist in multiple levels.
- Monster types gain new abilities at different levels.
- Monsters' abilities define their battle role in an army.

- Make some units immune to all physical damage, and others immune to certain types of physical damage (piercing, blunt, or cutting attacks). Suddenly, your melee champion is not so effective anymore.

- Each monster type should have a couple of varieties (Mama bear, Papa bear, and Baby bear as an example). More specifically, I think each monster type should not be restricted to one level, but appear in battles in a spectrum of levels. For example, Baby bear = level 1, Mama bear = level 3, and Papa bear = level 5. And to give a visual difference, unit sizes should scale up and down with level. So Baby bears look tiny compared to Papa bear. Moreover, as a monster's level increases, it gains additional traits/abilities with the goal being that different level monsters have different battle roles.

Examples

Fire Elementals
Imagine entering a battle against a eight fire elementals. Four are level 1, three are level 5, and one is level 9. The level 1s have the Flame Dart and Fireball abilities, they stay in the back row and always cast those spells. The level 5s have the Firestorm added to their repertoire. They always cast Firestorm from the back, or whatever causes the most damage, and will make melee attacks when the attackers close in. The level 9 fire elemental, it does not need those fire spells because its melee attacks are so strong. It's job is to close in with the attackers in melee combat and to keep them away from its lower level companions. To make things more interesting, the level 9 could have the "Ethereal" trait, i.e. immune to all physical damage. I mean really! How is a sword supposed to cut pure fire?
Not hard enough? Give the level 9 elemental the "Summon Fire Elemental" spell.
Still not hard enough? Since elementals don't really have shards, let's use the elemental's level divided by two as the number of shards to power up their spells.
With the enemy using powerful spells in this way, I would at least have a reason to use "counter spell".
Elemental armies could also be made up of low and mid level elementals for early and mid game adventurers to tackle.

Spiders

I like the Tangled Web ability and I think that is the most important ability unique to spiders (a unit immobilizer spell). But I think there should be more spiders  in an army who have that ability who will sit in the back rank and cast them continuously.

Let me give a few spider examples:

Black Widow
Tangled Web  (should have high rate of success >80%)
Level 1 - cast tangled web incessantly from the back row until they are brought into melee combat, then they bite their attackers.
Level 2 - Venomous I - while the level 1s are tangling their victims in webs, level 2 spiders attack a victim once, then moves to the next, repeat. (the idea being that the immobilized units will dies to poison )
Level 3 - Paralyze I - The Black widow paralyzes one victim for 3 turns. If victim is paralyzed, the level 3 spider will attack it with its "Venomous I" fangs till it is no longer paralyzed or dies.

Rock Spider
Immune to Cutting Attacks
Upon invading a Rock spider lair, the ground is randomly strewn with invisible spider webs. If a unit is caught in a web, the unit remains immobilized for 3 turns and the web is removed.
Level 1 - Straight-out attacks enemy in melee and acts like cannon fodder.
Level 2 - Spit Acid I - Stays in the rear and spits acid at enemies. Spit Acid should always hit immobilized targets.

I'm gonna say it again: A unit's abilities and spells should have high success rates and very potent or else they will not be feared, or even noticeable.

Similarly, these ideas could be extended to other monster types. With a full nine-unit army, with each monster given  a particular role to fulfill, monsters can finally make the wilderness a scary place at all levels.

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This also leads me to a related topic:

Single unit monsters and Player-controlled monsters

In my current game I have an ice elemental. It is level 4  ( summoned with 2 water shards). I have a mind to use it in my army, but it would be a waste. Currently in my game, typical unit sizes are 5, so it would die quickly to newly trained units. I think such single units, especially those without the overpower ability, should get a HP buff for their survivability. Also, for those who like to summon minions or tame beasts and utilize them in their armies, I think it would be more enjoyable for the player if they gained new traits/abilities as they leveled up like I mentioned in the Fire elemental example.