[Blitz]

The one that interests me specifically is the Shedu, as I might place Arco as my next Race. There was a discussion recently where some were saying the Shedu is a useful SC in the early game

Dude seriously don't believe everything you read. That thread was dedicated to some people wishing to prove he wasn't worthless, not that he was by any means the best choice, certianly not for a newer player =).

More generally, what specific items/spells make an SC?

For any supercombatant, I generally consider the bare minimum for magic paths to be earth level 3 and water level 2. Other magic paths can give bonuses, but generally these are the most important two. Earth 3 gives you the stoneskin/ironskin/invulnerability line, as well as the fatigue-reducing summon earthpower. Air 2 gives you Mirror Image and Mistform, as well as the mobility spell cloud trapeeze.

So for a bare minumum SC, playing Arcoscephale, you could try this:

Virtue
Dominion 7
EEE AAA

That leaves you with 280 points for scales and your castle... which is a lot. She's good in the early game because of her awe, and later you can add a haste item to make up for the lack of quickness.

However, spend a little more and you could have...

Virtue OR Nataraja
Dominion 7
AAA WWW EEE

Leaving 160 points for scales and castle. Either of these two pretenders with these magic paths cost exactly the same, the decision is made as to if you want 4 arms or awe and flying... plus an extra misc slot. The Virtue is more mobile and better in the first 15-20 turns, but in the late game, not much is better than a Nataraja with all the toys.

The water magic in the above two examples is for two things. Most obviously quickness, but less obvious is breath of winter, which is a cold aura which kills nearby troops.

Other useful magic paths are death magic (for soul vortex), and nature magic (personal regeneration, elemental fortitude). These are generally thought to be less useful than air, water, and earth... although I'm sure some would disagree.

As for equipment, one item stands out. The Wraith Sword will drain your opponent's life and add it to your own. This amounts to huge regeneration of both life and fatigue. Until you have a good grasp of SC's in general, use this weapon. Other critical items are the Pendant of Luck, and the Amulet of Antimagic.

If you were to outfit the above Nataraja, I would suggest the following gear:

Wraith Sword (life draining)
Charcoal Shield (Fire Shield)
Faithful (for luck)
flame helmet (fire resistance)
Hydra Skin Armor (or robe of shadows)
Winged Shoes (flying good)
Amulet of Antimagic (magic resistance)

For the Virtue, try this...

Wraith Sword
Flame Helmet (fire resistance)
Hydra Skin Armor (or robe of shadows)
Boots of the messenger
Amulet of Antimagic
Pendant of Luck

Good luck.