I have been using it exclusively this week, yes. It’s not as fast as a Maw/Mercy team but it is super reliable, and with 5* kingdoms it’ll win most matches in under 3 minutes. If the enemy front troop is Entangled, you can let it waste turns on skulls while you power up your generators. The only thing that poses a realistic threat is a team with several Impervious troops, but I’ve found that mana drain and true damage/AoE damage handles them well enough. I’m pretty happy with the investment in the forest dragon.
My record this week is 86 wins / 2 losses and I take on everything.
Of course, Famine is a great troop in its own right. I’d say he’s likely a better investment if you had to pick one.
I have returned with the math on Sylvanimora’s ability.
I found that the cost of 17 was acceptable compared to Behemoth’s 14. The following are all approximations but close enough…
Assume that on a given board, there are about 9 of each color (including skulls). Behemoth destroying 10 gems will therefore get one skull and 9 mana. Maybe 2-3 of that 9 mana will start recharging Behemoth. Comparatively, Sylvanimora will explode 24 gems, of which 2-3 will be skulls, leaving 21-22 mana - at the 70% rate for explosions, the gain is about 14-15 mana (4-5 going to Sylvanimora).
Behemoth does +1 damage*, Sylvanimora gets a decent amount more mana even after the extra cost. However, Sylvanimora can also control the columns to destroy - meaning the player can choose which mana to get (potentially recharging half or more of the cost), leave a skull match for the entangled first enemy to try to use, and so on.
So I think 17 is fair.
(*: 16 damage instead of 17, late-game, doesn’t mean much either - easy trade for board control effects)
I think the concept of an off-tank (position #2) works pretty well in a lot of teams.
I was actually using War in that role for a while - for difficult fights I knew were going to take some time. When the tank finally dies, you end up with this huge War ready to do some damage. It wasn’t exactly an optimal team in the meta at the time, but it was incredibly fun and reliable to play with.