You still get the 3 Elf bonus, but you should also get a 2 Forest of Thorns Troops one, and a green transformer.
Correct Bonuses are:
Lord of Spiders
All troops gain +1 Attack for having 2 unique Zhul’Kari troops
Lord of Thorns
All troops gain +1 Life and +1 Armor for having 2 unique Forest of Thorns troops
Elf Captain
All troops gain +1 Magic for having 3 unique Elf troops
By making the hero count as an elf, you give up either 2 magic or 4 attack. +1 magic for the team and being limited to mediocre troops isn’t really helpful.