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I obtained the RotHK, the orb of fire and water, opened the dwarven portal,cleaned the pyramid,made the dragon and the dog quest and all the elder dwarf ones too.

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fireballs is a good but a bit risky way to get into the bug temple in the first place, you need preferably high speed, a way of teleport + control (magic map). just wield 2 shields put tactics on coward (just in case) and teleport to the stairs and immediately cas a fireball, which will most likely take out the killer bugs around the stairs. and wands of door creation are your friend in the temple, just block all unneeded rooms.

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Wights, vampires, spectres and wraiths should increase your toughness if eaten. No, I don't know why either.
Note that this will push you towards chaotic. Other than that, there is no downside.
If available, use morgia roots before visiting the graveyards (which are, obviously, the places to go for the above corpses), since undead corpses will work for higher levels, i. e. above 25-27, the limit for morgia.
This is how I use morgia:

1. Eat 4 morgia roots of any b/u/c status
2. Wait (or continue to do something else, of course) till you get the "Your will seems inflexible. Your health increases." message.
3. Repeat, unless you do not have 4 morgia roots anymore. You can also eat lower amounts, but they will not work quite as well.

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Ogre cave, for eating ogre for +STR, and anytime you come across a giant corpse/tension room/vault. Especially if you have a ring of weakness.

These herbs will also take you to Starved quickly and reliably. Starvation will let you increase ST to about 40 and LE, WI, DX (mabye PE?) just by Giant corpses and herbs. Without ring of weakness.

Cursed -emptia is of course better than blessed. One of the few items in the game...

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Herbs:
Not counting the fact that when you get a stable, replenishing herb pattern you always get 2 (or 3) different types of herbs, my most-wanted herbs would be something like this:
1. Morgia root
2. Stomofillia/-eptia
3. Curaria/devil rose
4. Spenseweed
5. Moss of marilllon
6. Pepper/Burp root
7. Alruna/demon.

1. Always, grows two very useful stats, this would get lower on my list only if I had a fighter-type with very high toughness already. And these stats are very very hard to boost any other way
2. For both the herbs. Im really warming up to starvation. And fillia is good for getting (pre/post)crowned
3. If I have a character without the cure disease spell, I would need the curaria. If I have cure disease spell, this gets lower rating. Devil rose for the additional stat-increase.
4. Not higher? There are other methods of healing. I find myself not using artificial healing that much. Blessed Spense is a tad weaker than blessed peppers, but usable whenever is a huge plus as far as reliability is concerned. I always end the game with huge pile of these, as well as healing potions I never got to use.
5. Dex is very useful, it's not that. But still. There are other ways to increase it. And it's just one stat.
6. Pepper has an evil twin, and root is just useless, apart from allowing you to train first aid skill.
7. Not useless, but I usually have enough cure poison potions. And there are two spells doing the same work, and poison resistance is easy, so yeah. Mostly useless.