GDSM versus SDSM
Gray dragon scale mail (GDSM) and silver dragon scale mail (SDSM) are considered the two best suits of armor in the game. GDSM provides magic resistance and SDSM provides reflection, but it is not always clear which is better in any particular situation. If you intend to wish or reverse-genocide for dragon scale mail, you will need to decide which one is more appropriate.
Which armor is better largely depends on both playing style and one's current situation. A player who has one extrinsic should almost always wish for the armor which provides the other, but when one has neither, it is dependent upon things such as current hp, conducts, pets, and general style. For example, if you get an early wish and are not adhering to any conducts or time-consuming strategies, SDSM is often better. This is because you can wish for magic resistance at the Castle, which usually is before the threats MR protects against become too numerous.
Sometimes the armor that would be most useful immediately is not the one that you intend to include in your ascension kit. In this case, you must choose between maximizing immediate utility, and conserving wishes in the long run.
Gray dragon scale mail
- Magic resistance protects against many monster spells, including particularly nasty ones such as destroy armor and touch of death.
- Monsters capable of casting the more dangerous spells (such as golden nagas and liches) usually only appear relatively close to the castle. There, you will have more opportunity to wish for magic resistance.
- Bear in mind that attack spells generally require the monster to be in melee range, so careful use of missile attacks and/or Elbereth can mitigate this danger to some extent.
- Magic resistance protects you from wands of striking, which cannot be reflected.
- Wands of striking do much less damage than the elemental wands, and will not damage your equipment.
- Magic resistance provides protection from teleport and level-teleport traps, which can place unwary characters in dangerous situations.
- Level teleporters likely take you up. Fully exploring levels top-down makes those destinations safe.
- Magic resistance provides full protection from polymorph traps, and allows you to safely displace your pets onto them.
- SDSM provides partial protection against polytraps: you will turn into a silver dragon, trashing your shirt and cloak but keeping your armor. This will not protect you or your armor against subsequent polymorphs while in silver dragon form. Polymorphing in this way will revert your scale mail back to scales, negating much of its AC bonus, but not the extrinsic. Also, neither suit protects against polymorphs caused by lycanthropy.
- Reflection is usually easier to obtain without wishing than magic resistance, particularly because of the possible amulet of reflection in Sokoban and the possible shield of reflection on Medusa's Island. Spending a wish or genocide scroll on GDSM makes it easier to obtain both properties, since magic resistance would usually be obtained by wishing for a cloak of magic resistance or quest artifact anyway.
- Medusa's shield only comes rather late in the game, and close to the Castle wand of wishing.
- Obtaining magic resistance from your suit frees up your cloak slot. This allows you to wear something more useful, such as a robe or oilskin cloak.
Silver dragon scale mail
- Reflection protects you and your equipment from wands and breath attacks of fire, cold, and lightning, which are rather common and can deal tremendous amounts of damage.
- You can protect scrolls and potions against only fire and cold by placing them in a container. Rings and wands kept at the ready will still be vulnerable to lightning. In particular, only SDSM protects your escape items.
- Reflection protects you from a black dragon's disintegration breath.
- Reflection protects you from wands and breath attacks of sleep.
- Sleep resistance will also protect you from these.
- Accidentally attacking a floating eye will not paralyze you.
- Careful play will usually prevent floating eye accidents, as will a ring of free action.
- While both suits protect against a wand of death, reflection gives a chance of killing the zapper on a rebound, preventing him from wasting valuable charges.
- This does not apply to Orcus, who is a demon and therefore immune to his own wand of death.
- Obtaining reflection from your suit frees up your amulet and off-hand slots. This allows you to wear another amulet (such as life saving), and potentially allows two weapon combat and combat spellcasting.
- Magic-resistant characters take damage from anti-magic traps; for characters who luck into an early wish while still fragile, this could be lethal.
In general, one will still want to wish for GDSM or SDSM as a first wish in SLASH'EM, and all the above arguments apply much the same. However, lawful characters will prefer GDSM since they have access to minions including movanic devas beginning at level 7 and monadic devas beginning at level 10, both of whom have a 25% chance of being generated with a shield of reflection, which can be obtained by allowing the minion to be killed (easily accomplished by bringing them near the Oracle) or by stealing it while polymorphed into a nymph, pixie, quickling, or brownie. Conversely, non-lawfuls will prefer SDSM as any elven cloak has a 1/4 chance of being upgraded to a cloak of magic resistance if #dipped in a potion of gain level, or upgraded with the gnome's tinker technique.
Additionally, two types of dragon scale mail become useful in the later game, if one has other sources of magic resistance and reflection. These are deep dragon scale mail which provides drain resistance, yellow dragon scale mail which provides acid resistance, and shimmering dragon scale mail which provides displacement. Drain resistance is a somewhat vital property in SLASH'EM, with wands of draining being a prominent factor in the late game. However, SLASH'EM provides numerous other ways to get it, in addition to wielding Excalibur or Stormbringer. These include an amulet of drain resistance, some new artifact weapons, being a lycanthrope, necromancer, or undead slayer, or wielding the Hand of Vecna (which is an item all adventurers will want to get anyway). Acid resistance is more desirable in SLASH'EM because of monsters with very powerful acid attacks, including the feared giant shoggoth, and the lab coat (SLASH'EM's version of the alchemy smock doesn't provide MC 3. Finally, shimmering dragon scale mail makes it possible to get displacement without the cloak, which also doesn't provide MC 3.
In GruntHack, thanks to object properties, the discussion of GDSM vs. SDSM is superfluous. As you can wish for a dragonhide cloak of magic resistance of reflection which gives you an AC 9 cloak with both properties, yellow dragon scale mail is usually a better choice, especially given that spellcasters may cast acid blast at you.