How this one hasn't been made yet is beyond me.
If you haven't faced off against Magmortar at least once, then you obviously haven't been playing that much NU. Magmortar is definitely one of the most threatening Special Attackers in NU. Despite having a Stealth Rock Weakness, it easily makes up for it with its versatile move pool and decent stats. Magmortar is primarily seen as a Choiced User, but there are other sets that make Magmortar very threatening.
Move Sets
[SET]
name: Special Attacker
move 1: Fire Blast
move 2: Thunderbolt
move 3: Focus Blast
move 4: Hidden Power Grass / Hidden Power Ice
item: Life Orb
ability: Vital Spirit
nature: Timid
EVs: 24 HP / 252 SpA / 232 Spe
Man this thing is scary. Base 125 Special Attack means that Magmortar is going to be hitting a lot of things hard. Hidden Power Grass was mainly for Lanturn, but now it serves as a way to hit Quagsire. Hidden Power Ice hits the less common but equally dangerous Altaria.
[SET]
name: Choice Scarf
move 1: Fire Blast
move 2: Thunderbolt
move 3: Focus Blast
move 4: Hidden Power Ice / Hidden Power Grass
item: Choice Scarf
ability: Vital Spirit
nature: Timid
EVs: 24 HP / 252 SpA / 232 Spe
While it's not outspeeding Rotom-S, Scarfed Magmortar is definitely a very threatening revenge killer. Hidden Power Ice is more recommended for this set in order to defeat DD Altaria.
[SET]
name: Flame Charge
move 1: Flame Charge
move 2: Fire Blast
move 3: Thunderbolt
move 4: Hidden Power Grass / Hidden Power Ice
item: Life Orb
ability: Vital Spirit
nature: Naive / Hasty
EVs: 24 Atk / 252 SpA / 232 Spe
Flame Charge is a lesser seen but very threatening set. Flame Charge allows Magmortar to have the speed of a choiced user while being able to freely switch moves. While I disagree with having a Naive Nature (really should be Timid, what the hell are you trying to kill with Flame Charge :/), this set is definitely an underrated but viable set.
Other viable options
Hidden Power [Water]- ok, I know all of you are probably thinking why this? Well, right now, one of the best Magmortar checks in the tier is Camerupt. This not only completely catches Camerupt off guard, but it paves away a chance for some teammates that might have a hard time with Camerupt (Grass mons like Exeggutor or Cacturne)
Expert Belt- Feigning a choiced set is a fantastic way to get off some surprise kills. Ironically, no one ever seems to expect Expert Belt, since no one ever uses it. I have tested it out, and it works fairly well, luring in bulky waters thinking they can wall Magmortar only to be rocked by Thunderbolt the next turn.
Discuss!

If you haven't faced off against Magmortar at least once, then you obviously haven't been playing that much NU. Magmortar is definitely one of the most threatening Special Attackers in NU. Despite having a Stealth Rock Weakness, it easily makes up for it with its versatile move pool and decent stats. Magmortar is primarily seen as a Choiced User, but there are other sets that make Magmortar very threatening.
Move Sets
[SET]
name: Special Attacker
move 1: Fire Blast
move 2: Thunderbolt
move 3: Focus Blast
move 4: Hidden Power Grass / Hidden Power Ice
item: Life Orb
ability: Vital Spirit
nature: Timid
EVs: 24 HP / 252 SpA / 232 Spe
Man this thing is scary. Base 125 Special Attack means that Magmortar is going to be hitting a lot of things hard. Hidden Power Grass was mainly for Lanturn, but now it serves as a way to hit Quagsire. Hidden Power Ice hits the less common but equally dangerous Altaria.
[SET]
name: Choice Scarf
move 1: Fire Blast
move 2: Thunderbolt
move 3: Focus Blast
move 4: Hidden Power Ice / Hidden Power Grass
item: Choice Scarf
ability: Vital Spirit
nature: Timid
EVs: 24 HP / 252 SpA / 232 Spe
While it's not outspeeding Rotom-S, Scarfed Magmortar is definitely a very threatening revenge killer. Hidden Power Ice is more recommended for this set in order to defeat DD Altaria.
[SET]
name: Flame Charge
move 1: Flame Charge
move 2: Fire Blast
move 3: Thunderbolt
move 4: Hidden Power Grass / Hidden Power Ice
item: Life Orb
ability: Vital Spirit
nature: Naive / Hasty
EVs: 24 Atk / 252 SpA / 232 Spe
Flame Charge is a lesser seen but very threatening set. Flame Charge allows Magmortar to have the speed of a choiced user while being able to freely switch moves. While I disagree with having a Naive Nature (really should be Timid, what the hell are you trying to kill with Flame Charge :/), this set is definitely an underrated but viable set.
Other viable options
Hidden Power [Water]- ok, I know all of you are probably thinking why this? Well, right now, one of the best Magmortar checks in the tier is Camerupt. This not only completely catches Camerupt off guard, but it paves away a chance for some teammates that might have a hard time with Camerupt (Grass mons like Exeggutor or Cacturne)
Expert Belt- Feigning a choiced set is a fantastic way to get off some surprise kills. Ironically, no one ever seems to expect Expert Belt, since no one ever uses it. I have tested it out, and it works fairly well, luring in bulky waters thinking they can wall Magmortar only to be rocked by Thunderbolt the next turn.
Discuss!