Summoners War: Chronicles

Use Verdehile along with Elenoa, Tiana or Celestia and Argen or Narin Ha in a team composition known usually as trinity.

When combat start increase your Ultimate Gauge rapidly with Elenoa, Tiana or Celestia as soul link then swap your soul link to Verdehile and use your ultimate. Then use the timespan of Verdehile ultimate to spam damaging spells with Argen or Narin Ha to deal massive damage.

The use of the Enhancement Amplification artifact and focusing on attack speed and critical rate for verdehile as well as some precision will allow for massive uptime for the Mana Regen SPD UP, Mana Cost DOWN and ATK SPD UP buffs which will allow to spam damaging spells with your dps unit on soul link.

You have some leeway in the way you rune him in that you don't actually need him to do damage and have high ATK and Crit DMG to be useful, you only need to focus on getting Crit Rate to 100% and giving him as much atk speed as possible while giving some amount of HP to survive the occasional hit he's liable to take and a bit of Precision to actually hit his autoattacks to proc his passive as often as possible to maximize buff uptime.