Ask yourself this: "What was the purpose of shadowflame before it had a glyph" or "In what situation would I cast this unglyphed"
Maybe you're thinking, I use shadowflame for uber AoE damage! Um.. no. There is simply no reason to cast shadowflame over rain of fire/seed of corruption. As a source of damage shadowflame is just a joke. I don't want to dwell on the damage too much though. If I could fix shadowflame, I actually wouldn't make it do more damage. Warlocks aren't supposed to run up to melee for optimal damage.
The spell absolutely has no purpose unglyphed. I know a lot of people dismiss this saying, it has the glyph of shadowflame now, it doesn't matter.
That doesn't do it for me. Are you seriously telling me when WoTLK first came out Blizzard's plan for this spell all along was to have no purpose for the first 6 months of WoTLK and then they would bandage it with a glyph to turn it into cone of cold?
Any reasonable person would probably doubt that Blizzard PLANNED for this spell to have no purpose for 6 entire months.
Just having a glyph bandage the fact that a spell is useless baseline doesn't solve the problem. Glyphs are a feature of CUSTOMIZATION. When you start making spells only useful when glyphed they are no longer CHOICE but MANDATORY. Why have more than 3 glyphs if you're just going to make mandatory glyphs?
As a PvP'ing destro lock I already have enough mandatory glyphs with glyph of immolate, conflag and soul link. Shadowflame remains useless to me and I never cast it. I don't even bother with a key bind for it.
It just irks me. Blizzard is usually very reasonable. Every class got only 2 or 3 new spells in WoTLK. In warlock's case, we got 2. With such a small number of new abilities you'd think Blizzard would put some thought into them and actually give them a purpose.
What makes it worse is with the glyph shadowflame is basically cone of cold. Don't get tiki with me with the whole "lulz its diffrunt it slows 4 20% moar". It's ridiculously similar to cone of cold. I thought Blizzard actually agreed with warlocks for once that warlocks and mages have been homogenized enough.
Warlocks are a class in dire need of ACTIVE defenses. Shadowflame seems like such an obvious ability to tweak to simultaneously give this useless spell a purpose and give warlocks some defense. It could have a pushback, it could lower attack speed/attack power, it could disarm, it could disorient.
Locks only got 2 new spells in WoTLK. I don't think its so much to ask that both have a purpose (teleport works for me). It doesn't have to be great, just something. Give me a reason to give shadowflame a keybind.
Any input on what you guys think could be done to shadowflame to make it have a purpose would be great.