Hello everyone and welcome to my 209th analysis, this time featuring Volthar.
Overview: Volthar is a very fast Monster, outspeeding even the likes of Jasastur and tying with the ever-powerful Warmaster Thalassa. He currently is among the very small pool of Thunder Monsters to have access to Possession, and AOE Possession at that. He also has useful debuffs such as Shock and Nanovirus, which allow him to deal with damage boosters and extra turn spammers, along with having buff removal which is always useful. Having Tough as his trait is helpful in any environment and giving himself 100% Damage Mirror at the beginning of the battle helps Volthar punish attackers that target him. Despite these fantastic traits for a denier, Volthar is also plagued by their common burdens, such as being passive at times and being helpless against Monsters that are immune to his deny method.

-Divide And Conquer
-Tyan Gwat
-Ura Tsuki
-Dian Xue/Enemies Deception
Runes: 3 Speed
Mutant Rune Options: Speed&Life
Relics: Banners and Staves

Build Explanation:
Divide And Conquer is Volthar's AOE deny move, Possessing all enemies. Tyan Gwat applies Nanovirus, removes 30% of Stamina and applies Stamina Leak, to all enemies, making it good for stacking damage and Stamina Drains. Ura Tsuki also applies Nanovirus, but it's mostly used for its buff removal here, which can be used after DAC to apply Possession to enemies once again by removing the Recently Possessed buff. For the last slot, Dian Xue applies Shock to all enemies in addition to removing 30% of Stamina from them, which counters extra turn spammers and stacks Stamina Drain with Tyan Gwat. An alternative is Enemies Deception, which is simply a single target Possession to increase the amount of deny skills you have.
3 Speed is a must on a denier, and as for Mutant Runes, increasing your Life is the only noteworthy thing to do.

Teammate Options: Volthar doesn't have many unique interactions, so for Teammate options, check this article.

Countering Volthar: Warmasters Necromancer, Sherezar and Ragnarok all belong in the Spirits Book, and the first one gives his entire team immunity to Possession while the latter 2 possess CD Activation skills, which bypass Tough, and higher Base Speed stats than Volthar. For more Counter options, check out this article.