.Let Tiny upgrade toss and Techies, suicide.
.Aim for your target, choose the hero which has lower HP and has lower armor.
.Let the Techies always stand just near the Stone Giant to wait for the perfect time.
.When the time is right, toss the Techies near the enemy and let it commit suicide.
Kaboom! You just killed an enemy.
This trick will surely slows down enemy level up and harassing them can be very irritating. Not to mention the excitement of making fun with the game with this tactic.