Here are the stats for my OC Lucia Mochizuki (my avatar). Sorry for making a long post.
Age: 17 (16 March, 2202 AD)
Soul Gem: Spring Green
Weapon: Celeste (Spear with lightning element)
Tier: 8-A
HP: 2,750 / 2,750
MP: 1,400 / 1,400
Base Damage: 160-235 (2x if max HP is 20% or lower)
Physical Resistance: 30% (2x if max HP is 20% or lower)
Magic Resistance: 50% (invulnerable if max HP is 20% or lower)
Abilties: Can shoot chain lightning up to 3 enemies, every hit she connects with the pointy end deals halved damage to MP as shock in addition to HP, can deflect only energy projectiles.
She is very agile, somewhat strong, but not OP. In large outdoor battles, she can summon random mythological creatures to aid her.
When her max HP reaches 20% or lower, she will go berserk, doubling her base damage and damage resistance, and can call a thunderstorm that can deal massive damage within several klicks, but it only lasts for a few minutes.
Strategies: She is a tough cookie to beat, as her soul gem is on the crown, so about the only way to damage her is repeatedly hitting her on the head for full damage, whereas anywhere else will just make things harder. Once her HP is whittled down to about 1/5, immediately switch to melee, as she becomes invulnerable to magic at that point.
Upon defeat, she will scream in agony that can be heard for up to 5 klicks before vanishing in a flash of light.