Mel is getting a small rework in Patch 26.22, primarily targeted at reworking her [W] Rebuttal into something more manageable.
It's coming up to two years since Mel Medarda's release in League of Legends to... a mixed reception. The most controversial aspect of Mel's kit is now being changed in a Midscope Update that will go live in just under two weeks. You can play around with new-ish Mel on PBE, or read on to see what exactly has changed.
The Why & What
In a recent /dev drop by Kevin "Captain Gameplay" Huang, Riot went into the issues with Mel's [W] Rebuttal. Whenever a new champion is released, the goal is to introduce something new and exciting and that usually means coming up with a new mechanic. For Mel, that was her Rebuttal, which reflected an enemy projectile or spell back to their attacker.
There were a lot of issues with this ability and Riot has ultimately determined that the ability is too frustrating to keep working around anymore. They toyed with the idea of making Rebuttal her new ultimate, but that would require upping the power of an already difficult-to-deal with ability. Additionally, it'd require toning down her current ultimate which Riot thinks is in a good position and shouldn't be made weaker.
Mel's new Rebuttal will no longer copy an enemy's ability and send it back to them, but instead create a shield that affects her and any nearby allies. It will still destroy enemy projectiles and retaliate some damage, but you can no longer Seraphine ult the entire enemy backline with the [W] key.
For Mel fans, there's some good news though. Because they're taking power away from her [W], there's room in the power budget to buff her other abilities. Mel will now have better scaling overall, though a slightly weaker early game. The goal is for her to be able to take down more enemies in the future rather than only excel at single target damage as she does now.

Patch Notes
▲ BUFF | ▼ NERF | ▶ ADJUSTMENT | ✶ NEW
Statistics |
▲ Health growth increased to 107 to 99. ▲ Mana growth increased to 38 from 28. ▲ Attack speed growth increased 2.75% from 2.5%. ▲ Armor growth increased to 5.4 from 5.2. ▼ Base health reduced to 590 from 630. ▼ Base mana reduced to 455 from 480. ▼ Base attack damage reduced to 52 from 54. |

|
Searing Briliance passive |
▲ Minion damage stored increased to 55% from 50%. ▼ Base damage reduced to 4 – 30 (based on level) from 8 – 30 (based on level). |

|
Radiant Volley Q |
▲ Subsequent base damage increased to 5 / 10 / 15 / 20 / 25 from 5 / 7 / 9 / 11 / 13. ▲ Subsequent AP ratio increased to 8% AP from 5% AP. ▲ Mana cost reduced to 60 / 65 / 70 / 75 / 80 from 70 / 75 / 80 / 85 / 90. ▼ Initial base damage reduced to 60 at all ranks from 60 / 85 / 110 / 135 / 160. ▼ Initial AP ratio reduced to 25% AP from 55% AP. ▼ Explosion radius reduced to 200 units from 225. ▼ Missile speed reduced to 3200 from 3800.
✶ NEW Cooldown is now reduced by 0.5 – 1 (based on level) seconds if the volley hits an enemy champion. |

|
Rebuttal W |
✶ REWORKED ✶ Mel creates a 400 unit nova around herself for 2 seconds destroying all enemy projectiles, shielding herself and allies for 50 / 80 / 110 / 140 / 170 (+ 50% AP), and granting 10 / 15 / 20 / 25 / 30% (+ 4% per 100 AP) bonus movement speed. Destroying a projectile retaliates against the source enemy, dealing 35 / 40 / 45 / 50 / 55 (+ 10% AP) magic damage, reduced to 5 / 10 / 15 / 20 / 25 (+ 5% AP) per subsequent projectile, up to a maximum of 7 per target.
▲ Cooldown reduced to 30 / 28.5 / 27 / 25.5 / 24 seconds from 38 / 35 / 32 / 29 / 26. ▼ Mana cost increased to 100 / 75 / 50 / 25 / 0 from 80 / 60 / 40 / 20 / 0. |

|
Solar Snare E |
▲ Mana cost reduced to 40 / 50 / 60 / 70 / 80 from 50 / 60 / 70 / 80 / 90. ▼ Root duration reduced to 0.8 / 0.85 / 0.9 / 0.95 / 1 seconds from 1.5 at all ranks. ▶ Slow changed to 20 / 25 / 30 / 35 / 40% from 30% at all ranks.
✶ NEW Root duration is now increased up to 1.6 / 1.75 / 1.9 / 2.05 / 2.2 seconds base field distance. |

|
Golden Eclipse R - Ultimate |
▲ Cooldown reduced to 120 / 90 / 60 seconds from 120 / 100 / 80. |