I first read the 50% extra turn suggestion in this thread: Balancing Suggestions and Ramblings
But I believe it was also brought up again by some others when the last delve came out because those troops have only a 30-40% chance of an extra turn. I know Goblins have this “niche” of always gaining an extra turn, but when your entire team is Goblins and you effortlessly refill mana, it becomes tiresome to play against. That’s why they nerfed mana gained from explosions years back. What they didn’t do was combat mana gained from mana generation. Now instead of Goblins just exploding gems, they’re creating gems (King Gobtruffle and Norbert’s Turnip) which isn’t affected by that nerf.
The counter is freeze, which isn’t viable against Medal of Orpheus or in Guild Wars weeks where color restrictions severely limit your ability to freeze enemies.