I did a stealing spree all the way to Reha in the beginning, So I came out of there with 19 Tirex eggs and started using them since battle 1. Free units for the win
Sprites and Fairies can ruin a no-loss game, especially as a Mage. In fact any unit that is low on HP can do that.
What was fun about that playthrough, was that I had to utilize every single bit of knowledge about this game in order to pull out a no-loss victory

The Mage hero is really hard, so a lot of intellect and unusual cunning are called for