Gerin: How can I raise his health? When I make items I only see ways to raise defense, and since Zaldron will never ever be in melee I wouldn't use that.

rakenan: Zaldron is great for staying at your fortress helping you research and cast spells. He's not going to win many battles without assistance, though, unless you get him some powerful items. Get him early and if you start to fill up your hero roster, dismiss or kill him when he's outlived his usefulness.

hansappel: He'll never outlive his usefulness. As he levels up, he'll contribute more and more to your research and spell skill. The only reason to bring him into battles though, is to give him experience quicker. So you can put him in your fortress to help him with spell-casting.

Spell skill is overall an underrated power. The only way to increase it, aside from having caster heroes guard your fortress, is to wait. It'll raise slowly over time. If you raise your skill staff you can make it raise more quickly, but you don't want to lower the research and mana staves. Well, the mana staff you can actually lower if you have Alchemy, as it's usually easier to simply make lots of money and convert it to mana.

However, spell skill can really turn the tides in battles. Let's say you have a single spearman unit in each of your cities, but a few books in life and decent spell skill. Well, now you can ward off most attacks by casting Invulnerability, Heroism and/or Healing on those spearmen!

rakenan: Spell skill is amazing, but it's also pretty common among heroes. Zaldron just doesn't bring enough to the table to keep him once you can start summoning, rescuing, or attracting champion grade heroes. He may not be good enough to keep even once you can attract the higher quality non-champion heroes. He is, however, amazing at the start of the game - thus, I keep him. Later on, if I have use for more than 5 heroes, he's probably going to the bucket.