ABOUT POTIONS
In the period when you don’t have much money yet, buy only small red pots from Pepin. These are three times as cheap as those big red one’s, and fill most of your ball per drink. When money isn’t a real problem no more, buy only big reds. And when you’ve got plenty of money, buy only big yellow one’s. These fill both your health and mana ball completely. Because Pepin only has a few of them, visit him every time you’re in town.
OBSTACLES, WALLS AND DOORWAYS
Use obstacles, walls (even better: corners) and doorways. It’s really simple; where a wall or obstacle is, a monster can’t be. The max number of monsters around you is 8, when you stand against a wall, it’s 5, and when standing in a corner it’s only 3. But watch out! Standing in a corner means retreating is almost impossible.
So walls or obstacles decrease the max number of monsters around you, which makes it easier for you. Doorways are even better; stand right behind them, and only one monster can face you (there can only be one monster in the doorway itself.) The mob behind this monster has to wait till this monster is killed, then the next one can face you. This way you can kill hordes of monsters without any trouble at all. Watch out for Goat clan’s; sometimes one slips through the doorway, and will go stand next to you, while another one appears in the doorway. When you face some Goat clan’s, simply hold down the shift key, and swing in the air in the doorway. Every monster that wants to face you (by standing in the doorway) will get hit before entering the doorway. This way they have a really hard time reaching the doorway, and thus makes it way harder to slip through.
When there are ranged attackers in that room as well, who are NOT immune to fire, cast some firewall on them. They’ll die because of the fire, while you kill the melee monsters one by one.
SHIFT KEY
In the previous section (about obstacles and all) you found one good use of the shift key (hitting the monsters back before they can stand next to you. But there’s another one. (I found this one on Bolty’s page:) When you’re chasing a monster that’s only two steps ahead, hit the shift key and swing at the monster (by hitting the left mouse button as well) This way you can hit and stop the monster (as long as your chance to hit is high enough), and thus kill it.
CORNERS
There is another way to kill monsters that flee from you; just drive them into corners and stand diangonally in front of them. It's as simple as that.
This way the monster won’t know where to go. It can only go up, or to the right, but eitherway it’ll still be directly next to you. No progress, so it won’t move.
PEEK-A-BOO
Although I already used this method, I found the term peek-a-boo on Bolty’s page. The peek-a-boo method is another way to kill those annoying ranged attackers that flee from you when you come too close. Just retreat around a corner when you see one or more of these “flee-ing ranged attackers.” Because of this you won’t see the monster no more, but the monsters can’t see you neither. They will walk to the corner where you disappeared (and where you lie in ambush.) They will appear right in front of you; which makes it very easy for you to kill them. Repeat as often is necessary (if there is more than one monster.)
The picture above shows Sir-Gabriel cornering a witch in a 'slaughter chamber'. These chambers can often be found and are ideal to peek-a-boo witches (next to the entrance) or to drive them into corners. They are safe, and you don't have to walk through half a level to get to a corner.
TELEKILLING
A really good tactic I found on Bolty’s page. Telekilling is yet another way to kill those annoying “flee-ing ranged attackers.” Because these monsters run as soon as you come too close, you’ve got to be next to them before they start to run. “How?” Teleport next to them, and then finish them off quickly. This is a very useful tactic when you’ve got teleport of a decent level and enough mana to cast it several times.
You can find way more about telekilling on Bolty’s page.
MELEE MONSTERS
Let the melee monsters come to you. If you don’t, you’ll probably activate more monsters, which makes it only harder. Impatience can kill!!
MORE TIPS
More tips in the "General tips" chapter. I also recommend visiting Bolty’s page.