Tyrell is a free unit available from the "To Burn with Life" event quest. He is a knight with a good amount of crit rate to deal damage, and can fill the role of a "breaker" because he has Trinity Break, making him a good unit to bring against strong single enemy quests/raids.
His crit rate comes from his board stats, TMR, and passive, totaling to 52 crit rate. Even more if you use Sharp Spear from Lancer subjob.
Aside from being able to deal damage, he also has enemy stats reduction skills like Power Break, Magic Break, and Trinity Break, which are quite useful, but may not be that necessary if you already have a strong tank, or high lvl gears that give high resistance to a certain attack type/element. However, bringing a breaker can help increase survivability since it works against most enemies.
Since he's a free unit, it can help most players build a f2p friendly mono water team easily because of Tidus, and Creysse, who happens to be good free units with water master ability buff. Then, having a unit like Ildyra that can fill the role of a healer can make a it more versatile. Finally add in a Siren VC and do water chains to be able to deal high damage.
His tmr is a decent accessory for the crit and acc for some players, there are better UR tmrs, but with the new azure frags you might as well get it, but his stats are SR tier so not worth leveling or job materials
Whats that move in the picture? I cant find anything has that range on him in global
Christ no. It gives okay stat boosts but it has no additional effect and it's stat boosts are ones commonly boosted by other TMRs or even regular equipment. A TMR requires both Max LB (fairly easy) and 6 RAINBOW SHARDS to fully awaken him. Not worth it.