Ah. Medusa liked my attention to her so much, and the fact that she's the only 3★ servant who reached lvl 100, that she decided to call her alternate version so she could become really strong too.

Though I don’t even know how good Ana is.

Imo, she's bad. But that doesn't matter. She's cute, and she's Medusa. That's all it matters.

I think you treated Medusa very well, which led to the 2nd copy of Medusa Lancer appearing.

Her skills are not great. Two have been buffed, but she still has issues. Her S2 damage buff is a 1 turn 30% attack boost. Her S1 charm couldn't even hit 100% originally, but has been buffed to 100% and adds 3 turns of Quick Resist Down. S3 is a combination 3 turn guts and 1 hit of invincibility, which was later buffed with a 30% battery, making it her most useful skill.

Her NP is the best thing she has since it was buffed only a year after she was released, making up for her abysmal unbuffed skills at the time. It still isn't amazing, but at least has another 3 turn Quick Resist Down debuff on it (after NP). Other than that, it is only damage and a chance of stun depending on overcharge, which is resisted by most Archer servants thanks to Magic Resistance being common for the class, only Billy the Kid and Super Orion lack it.

All told, you should only look at her if you lack other options, and given Evocation Festivals already added the much better Summer Yu, you can safely skip Medusa Lily.

IMO she's pretty underrated. I've beaten quite a few Archer bosses with her including the final battle in LB4 and was kind of surprised how easily I beat them. Her NP is quite good and hits hard. Her skills are not great but at least she has decent survivability which is always nice on Quick servants. Her NP gain is horrible which is what holds her back most. She's not top tier but nowhere near as bad as a lot of people rate her.

Even Romulus can beat both Ash and Tree of Emptiness easily 🤷‍♂️