Just suggestions but please consider.
Lava ballon that spills hot magma hound remains onto only a two tile radius underneath or above, traps that have specific spells in them; ie. Hypnosis trap (turns a small radius of attacking troops into defenders for a short time), vampirism trap (steals attacker's HP and uses it to slightly heal surrounding buildings), and last but not least, the portal trap (sends one troop that steps on it to the edge of the map, only works a few times before repair, and does not work on wizards, witches, or heros). All spell traps are rearmed through the spell factory.