[Aerich]

On mc vs dc - a F[7]/Cl will have the same effective thaco as what level of mc F/Cl? If you play on high level difficulties, and/or the entire HoW and TotL expansions, a mc should end up with a better adjusted thaco than a lvl 7 (or even lvl 9) dc.

A cleric/mage might survive as a defensive tank, but would be terrible at dealing out damage, except at quite high levels. I wouldn't recommend it - the spell usage it would require to be defensively and offensively effective is quite heavy. Look at it this way; a lvl 7 paladin specialized in longsword attacks twice per round with +1 to attack, +2 to damage, exceptional strength bonuses to attack and damage ranging from +1/+3 to +3/+6, and a warrior's thaco of 14. A lvl 7/7 cleric mage (I haven't compared the XP required for each) has thaco 16, one attack per round, no specialization bonuses, and at most a +1/+2 att/dmg strength bonus for 18 Str. It's a big hit to the natural offensive capacity of a frontline tank. Paladins can also use all of the warrior-specific items (especially potions of giant str and heroism), and can wear armor without worrying about spellcasting.

I view my tanks not so much as a front line, but as a front character that takes the brunt and a few other characters who jump in as necessary to deal out damage and take a bit of pressure off the main tank.

The three keys to tanking are 1) physical placement 2) spell tactics and 3) concentration of items and defensive spells on the tank.

Draw enemies back to a narrow bridge or doorway where they engage your best-protected tank first, and give your tank plenty of missile and spell support. Make them run through webs first so only a few get through at a time, and try to damage the stuck ones with spells and missiles so they are hurt by the time they can attack your front line - summons and charms can prevent enemies from even getting that far. Make sure the main tank has suitable protective spells cast upon it.