Is Carnage Titan any good?

Quick answer: "Yes, it is amazing ... if you can fit him in."

Why is he amazing?
Reach, Double strike, Shield. A Dragon! A perfect kit for almost any situation. I would argue he is the best second spot card in the game right now. He is vulnerable to magic, but we can put him behind a magic shield like Baakjira.
He is mana expensive, but with larger mana cap we have now, we can use him in many games. I managed to use him in two thirds of games I played with a Dragon summoner.
As 11 mana card he is vulnerable to Giant Killer, but he has Shield so it does not matter.
In no magic games we can even put him in the first spot due to bulkins and Shield.

Check some games

I won most (6/7) of the games with him, and I havent played against him yet so I can't say how hard he is to kill. You can check my games here:

• Large mana cap: https://splinterlands.com?p=battle&id=sl_d430e6b5e8143ef7d23155336ab3161d&ref=chicknorris
• Melee Mayhem ruleset: https://splinterlands.com?p=battle&id=sl_8f68b50febae89b667e99b11867d47f6&ref=chicknorris
• Medium mana game: https://splinterlands.com?p=battle&id=sl_cc96f17193172b644c148a135264232e&ref=chicknorris
• As a tank: https://splinterlands.com?p=battle&id=sl_8706de2b1abe2ab397eff52cf2039f48&ref=chicknorris

Combos

As a Reach monster and a Dragon Carnage Titan is easy to combine with any tank. He works great with any good first spot card (only CL card comboes):

• Baakjira,
• Grum,
• Grund,
• Forgotten One,
• Mycelic Infantry,
• Cursed Windeku,
• Diemonshark,
• Pelacor Mercenary,
• Nectar Queen,
• Pelacor Conjurer,
• Pelacor Deciever,
• Nightmare,
• etc.

Comparisson to Grum Flameblade

Both being 11 mana melee legendary airdrops this question comes naturally: "Which one is better?"
The answers might be different for every player and every strategy, but in general I find Titan much more useful for the general player.

Grum is very situational - speed of 1 is not really what you want on a monster with Bloodlust. If he can't hit, he can't kill, therefore he is just a big meat shield. He is great in Reverse speed and as a Magic shield.

Titan on the other hand is a Dragon, so we can combine him with other elements. He is vulnerable to magic, but he has reach so you can hide him behind Baakjira, Void Dragon or even Grum. Double strike is one of the best abilities, because it breaks the Armor or Divine shiled, can kill one enemy and attack the next one etc. With the Shiled he can tank a ton of melee damage - support him with Merdaali Guardian or Adelade/Renova and he can survive the heaven falling on his head.

Most efficient level

Best price/effect ratio is at 3* or the Gold league. Extra damage at 4* can help, but it will often go to waste anyway due to armor, low HP etc., and the price is almost double, so it is up to you.