New player seeks advice about playing a mage and the tactics for no loss

[Metathron]

In my opinion royal snakes are one of the best, if not the best, units in the game relative to level. Even without any artifacts they are awesome, but the boots are an excellent investment on your part, as it very often happens that the snakes need just that extra 1 point of speed to attack the enemy in their first turn.

Forest fairies -- and any other fairies for that matter -- are also very good units, but you won't be able to replenish them until you get to Elon, the elven continent, unless you use a trick wherein you leave your army behind and attack an enemy stack, in which case you'll lose the battle automatically (of course), but you'll get a new batch of your starting troops (bowmen, swordsmen and fairies, IIRC).