Letalis was a prophet, but he was condemned and killed by a king who did not like the future that had been predicted to him. However, because death wasn't his destiny to die, he has come back from the dead to fulfill his destiny and predict the death of others.
Letalis is a Dark denier. He's basically a Cosmic Pierceid, albeit having different methods to deny, and a rather weird skillset. He has three Freeze skills as well as two Stun skills, with both effects having an AoE. However, his Stuns only have a 50% chance to land, which is why he has True Vision as a Status Caster and as a skill that comes with Space-Time, nullifying damage. He also has access to 3-Turn Death Countdowns, a pretty nice feature since he can stall by denying, in which he has a single-target freeze and his AoE stun that both include death countdown. However, he can't stamina drain as a denier without letting go of revival when he has terrible life, or getting hit with it.
Letalis / Tabora / Shelly (or Bombeta instead of Shelly): Assuming the monsters are at least Rank 3 so Letalis can access True Vision, this is a great team set up mainly utilizing Letalis' 3-Turn Death Countdown to kill off enemies. This team works great unless the enemy has Mega Taunt. Bombeta, or Shelly, is obviously just there to tank up hits if the enemy somehow goes first. Tabora goes first and trait disables all enemies so that any Sudden Death, Stun or Freeze Immunities, clearing the way for Letalis to dominate. Letalis then does his AoE Stun and 3-Turn Death Countdown. Tabora can do whatever and Letalis goes ahead to Freeze all enemies. Then, Letalis stuns any monster with NER so they can't take away the Death Countdown. Next turn, all enemies die.
Letalis / Tabora / Fampirastral: This team functions the same as above, however, Fampirastral is included. Only use this team if you are sure all your monsters first in the turn order, otherwise you'll mess up. Fampirastral removes Mega Taunt just in case, then she does whatever she wants to cause havoc. Tabora trait disables, Letalis does his whole Stun then Freeze, Stun the NER and enemies are all dead.
Monsters with any form of Stun or Freeze Immunity takes away Letalis' main gimmick and monsters immune to both, such as Ourosmic and Fampirastral, makes his denial useless.
Monsters with NER, such as Luponudo and Tabora, that don't get denied by this monster can easily cleanse their whole team of the death countdown, taking away his main gimmick.
Strong Light attackers like Lightmare, Zuperfox and Diegael can easily defeat this fishy prophet.
Undead Mr. Beast is an amazing counter as he has Control Immunity as well as Death Countdown Immunity, making all of Letalis' gimmicks useless.