Personally I used Phantom + Horsemen a lot in my first game, and now I would use Magic Spring on the phantomed stack if I had Higher Magic. Phantom is also great for Griffins.
IMO Horsemen, Griffins and Roysl Snakes are among the best melee units in the game.
Phantom + Kamikaze + Griffins is also a great trick if you have Distortion 3 and Chaos 3. Phantom the Griffins and send em in to battle. Watch them retaliate and soak up hits from the enemy. If you are lucky they will last until turn 2, so Kamikaze them and BOOM! You've severely weakened the enemy without losing a single troop (unless the enemy has ranged units). If you have Higher Magic you can cast Phantom and Kamikaze on turn 1. This is basically a 'terrorist' strategy.
I love this game because it rewards intelligent and strategic thinking. Massive fun to be had!