When designing new monsters for your variant, it is helpful to keep in mind the various resource pools that the character has.
Strategic resources can't be recovered very quickly, and therefore loss of one of these resources affects the player's strategy. In theory, nethack has lots of different strategic resources, though most of them are either rarely damaged, trivially fixed, or are prevented by one of the mandatory resistances.
- HP: The main combat resource. Most monsters reduce HP, even if they also target one of the character's other resources. At low levels, HP recovers fairly slowly, so a tough fight can leave the character injured for the next hundred turns or so. At high levels, the HP regeneration rate is so high that HP becomes more of a tactical resource.
- Energy: A major combat resource for spellcasters. Though monsters rarely target this stat directly, casting spells reduces this resource. Again, at low levels this recovers slowly enough that choosing to cast spells has strategic implications. Unlike HP regeneration, a character's intrinsic energy regen rate never becomes so fast that it totally overcomes the effects of casting spells. However, wizards obtain greatly amplified energy regeneration from their quest artifact.
- Experience level: Because the existing drain life attack is resisted by Magic cancellation, and because a single drained level is easy to recover, in practice this is not a very significant form of damage.
- Inventory items
- Ability scores: Note that ability score damage can be trivially fixed with a unicorn horn (for this reason, some variants remove this power from unicorn horns). In theory, many vanilla monsters target ability scores. However, most such attacks are poison attacks, and poison resistance is mandatory due to the threat of poison instadeaths.
- Life saving: This is effectively the resource that instant death attacks target. Because instant death effects are more common earlier in the game (poison, death magic before MR is acquired), most instant death effects hit characters without Life Saving. Late in the game, not all players choose to equip LS amulets, and since amulets are the only source of Life Saving, making instant death attacks more frequent would further constrain the ascension kit.
- BCU of gear: This is one of the main late-game clocks. The player has a (moderately) finite supply of holy water, after which the character's weapon, luckstone, and bag of holding become liabilities.
- Erosion of gear: Because this is capped at -3, and because late-game gear tends to be naturally resistant, erosion is not really a factor in the late-game.
- Max HP
- Enchantment of gear
- Character memory
- Grease on gear: Because this protects against YASD from drowning attacks and brainless-ness, many players consider grease extremely important.
- Lizard corpses/Potions of acid
These resources exist, and at least some of them could be targeted by attacks, but no vanilla monster directly targets them.
- Prayer timeout
- Wishes: This is more of a meta-resource, and it would be hard to target directly, but leftover wishes can be an important source of flexibility for a late-game character.
- Intrinsic AC
- Intrinsic to-hit
- Intrinsic damage
- Spell memory
- Speed: The ability to take more than one step per one step of your opponent is an important tactical consideration. This enables the player to kite enemies, greatly reducing the damage taken in combat. Monsters that reduce speed target this resource, though few (no?) monsters do this effectively.
- Choke points: Fighting enemies at choke points is another important tactic. Monsters that dig through walls and doors target this resource.
- Cleared rooms: Retreating towards safe territory is another important tactic. Teleportation and level-changing effects target this resource.
- Free squares: In order to retreat towards cleared rooms or kite enemies, the character requires clear spaces around them. Summoners (and to a lesser extent, enemies that travel in packs) target this resource.
- Spirit powers: In dNethack, spirit powers are an important tactical resource, and properly managing their cooldowns and deploying each power for maximum effect are important parts of Binder gameplay.
- Pet position: The relative positions of you and your pet are an important tactical consideration for players attempting to make use of their pet. Reloctation traps target this, as do monsters able to temporarily (or permanently?) take a pet out of the fight.
- Visible squares: It is quite important to be able to see enemies coming. Monsters that spread darkened squares target this resource.