Fire Garo (Garo)

This is in my humble oppinion the most overrated monster in this game by far.
Maybe Garo can be a threat for noobs or people that face him the first time, but to be honest he is really easy to kill, a single multi-hitter will do the job, and there are lots of 3*-4* water monsters with multi-hit attacks: Stella, Chilling, Sabrina, Reno,Julie, Mihyang, Xiao Lin, Yaku, Tarq (S3), Su... also the fire monsters like Raoq can be a threat for Garo.
I know Garo can deal some decent damage and is usually a fast monster, so when I met him in dfense, my tactic is to just outspeed him with a def breaker like Orion and just finish him with Stella, Chilling or Sabrina. That simple. He just won´t have a chance to survive.
On the other side, Garo can be very useful when attacking, giving fire units an awesome speed bonus and dealing great damage specially to wind enemies.
So, even when overrated (or that´s just what I think), he´s a good monster to use on attack, but imo he´s to easy to take down when defending. I´ve fed a lot of Garos before he was buffed, now I don´t know if I will build one if I can get him, but if any of you already have one, he´s a good nat4 damage dealer and can be a key monster when properly used in offense, specially in siege 4* battles.

Check this video, you will change your opinion

How about vampire rune? it s suitable or not?

I have mine built on Vampire and works good. I prefer it over Violent or Swift, but it´s just personal.

INTERESTING FACT ABOUT GARO:
While I still think Garo is easy to defeat, he can be a real pain for heavy single target nukers. One "trick" of this unit is using him to tank Akroma to death in the feared Akroma+2xZaiross TOA/TOAH stage. As long as you can kill the dragons and keep Garo alive, he will defeat Akroma alone with a 100% sucess rate. The Valkiry cant just kill Garo. It can take 5 minutes or one hour, but Garo will eventually win the battle.

REVIEW UPDATE
Well, my own experience with Garo has oblied me to write this: I don´t think anymore he´s the most overrated monster in the game. Athough I still feel he´s "a little" overrated, like when he´s banned in RTA before Amelia or Diana (it happened SEVERAL TIMES to me), Garo has made me change my mind about him.
I mainly started getting curious about him in the famous Susano-Orion-Garo Siege defense. Facing that defense I started learning how annoying a properly built Garo can be.
Then I build one with decent runes, skilled him and had some fun in the Special League RTA 20*. And finally gave top runes to my Garo and I now use him in a lot of scenarios, not only the ones related to 4* monsters.

I can Use Garo in Arena as Fire leader, along with Shaina, Maruna, Chloe and/or Harmonia. He performs great. I also use him to farm the Dimensional Hole in both Karzhan scenarios. Of course he´s a must in attack/defense 4* bases Siege and finally he´s quite good for some Laby stages, usually as speed leader like in the arena. I´m thinking in build a second for siege, because the Susano-Orion team is good, but I´ve found out that Garo-Racuni-Skogul is an awesome team too (also building a second Skogul XD)

So despite my initial thoughts about him I´ve found Garo one of the most useful 4* monsters due to the wide range of scenarios you can use him in. Concerning runes, I think the most viable sets are Swift and Vampire, being Vampire my favourite by far. The build I´ve chosen is SPD/CrDam/%ATK. Mine is Vampire/Guard, the Guard runes are only for the SPD and ATK substats, giving me very good stats (249 SPD on Vamp is pretty good). Get SPD, CrRate and CrDamage as much as you can. And use S2 wisely, the stun can be a game changer in Siege.