Persona 3 Portable

This achievement is tied into the first major boss of the game. The bosses are themed around the arcanas that are part of the foundation of the Persona franchise and are called as such, the Priestess is the first you'll confront. She possesses an Assault Drive Strike-type attack as well as a pair of Ice-type attacks, Bufu (single foe) and Mabufu (all foes). She also has two status afflicting spells, Pulinpa (Panic) and Marin Karin (Charm), which will impact negatively your ability for command actions on your party. She'll also summon a pair of Muttering Tiaras, which you've encountered previously in your voyages in Tartarus. The only type of attacks Priestess holds any form of resistance to is Ice (she's also nullifies Light and Dark attacks, but chances are you don't have a Persona that has those types of attacks yet, but worth pointing out for everyone), in that case she repels and damages the user, so avoid using Bufu (though Muttering Tiaras are weak to this (as well as Wind), and you can get One Mores this way, but beating Priestess is what will end the battle, as she'll continue summoning them after you defeat the initial pair, albeit only one at a time). You'll be mandated to partake in this battle on 5/9 as part of the main story, and worth noting too that like the boss battle you had against Chairman Okumura in Persona 5 Royal, you will be going against a time limit here...not only will the countdown clock start where you have to get around a few lead up Shadow enemy battles before confronting Priestess...you'll have just EIGHT MINUTES to do it all. So knowing how to prep ahead will be key in defeating the boss without a whole lot of tension.

In hindsight, much of the prep work begins with your first venture into Tartarus, where the first block of floors is open up to 16F. Three sets of minibosses will await you in 5F (Venus Eagle x3), 10F (Dancing Hand x3) and 14F (Rampage Drive). When you defeat them and ascend to 16F, you can now strategize money and XP farming, and also acquiring excess sets of weapons and equipment that you can sell at the Police Station in Paulownia Mall for even more money, be it from chests you find in the dungeons or from bonus card shuffles that will pop up occasionally after winning battles, where money and XP bonuses can also be found, in addition to new Personas. Lastly, the Police Station will offer more powerful and stronger sets of weapons and armor starting around late April, with weapons boasting ATK stats in the mid 50s range, armor for DEF in the upper 40s, and footwear boosing EVA to over 20. The goods will also be sold at a discount on select days, in these cases 4/27 and 5/4, so plan your purchases around these dates if you care about saving up. Where your party should be at level wise, I would have the MC at least at level 12, and Yukari and Junpei each at level 10, with the MC's Personas at least at level 6 and at least one of them having an Agi spell in their moveset, as most of the enemies you'll need to beat in the leadup to the Priestess boss are weak to it.

On 5/9 at the Dark Hour, you'll go through the storyline as you and your party enter the monorail station to find the Shadow that has been detected outside of Tartarus. Once you get on the monorail train, you will come at odds with Junpei over how to approach a Shadow Mitsuru sees as a potential trap, leading him to bolt forward on his lonesome, and now leaving only you and Yukari for which to venture on to try and stop him. You will need to win consecutive battles against Shadows beforehand. The first one is two Muttering Tiaras, and the second also features that same pair, but also includes the Heat Balance enemy. Ice and Fire is their resistances, Electric and Wind are their weaknesses. Once you defeat them, move up the monorail cars and you'll reacquaint with Junpei, who's fighting Heat Balance, Dancing Hand, and Spurious Book. The latter two are weak to Fire. Once you beat them, the countdown clock starts. Yet another battle ensues, this time a pair of Dancing Hands as well as a Laughing Table. Thankfully they too are weak to fire. Beat them, and move further up the train, and you'll fight two more Shadow battles before the Priestess...first one is against two Muttering Tiaras and the Trance Twins (weakness to Ice is what they all have in common) and the second is Magic Hand and Obsessed Cupid. While the latter holds no weakness to Fire, if you've leveled up your characters enough you can still take them out in one Agi or Maragi blow.

Now, you have just the Priestess to finish this quest. If you desire to end this battle quicker, it's a good opportunity to use a stat altering spell, particularly a debuffing one like Rakunda on Priestess, if you have such a move available in MC/FeMC's Personas. When she starts summoning Muttering Tiaras, it's arguably a better bet to ignore them in terms of directing your magic attacks...you'd much prefer having your turn go for naught on an attack directed at Priestess as opposed to a Muttering Tiara you can get a One More out of. Once she is defeated the Tiaras won't matter...the battle is won. Once you get through the battle results and the post-battle cutscene starts, the achievement pops on-screen.