The Last Trial is the easier one... just use Little Hobbit, Goblin, Dwarf Defender, Succubus, Elf Hunter and Centaurion.
The Hobbit, Goblin and Dwarf, will keep the distance of the swordmaster and your Ranged units, if the swordmaster came close to your ranged, use the wall to keep her away... in less than 10 minutes she will be dead (:
Thank you!