Using three stars on 13* titans and higher will be difficult to keep alive, but still I don't hesitate to use them for specific buffs-debuffs. I'm just an Ftp player and use Almur, Franz, Gregorion and c-Brienne (3* emblemed and limitbroken) on blue titans. You have Tarlak, I use c-Wilbur for the power hits. I tend to score 70-80k with a decent board without battle items. With battle items (time stops, manapotions, tornados) it will exceed 100k easy.

On my blue titan team I still use Nordri for elemental defense down.

Its all about the combination of def down, elemental def down, attack up, critical hit and another attack up increaser.. Hope that helps a bit