Evolution
Crossbow Description: Shoots rebounding projectiles, penetrating enemies.
Crosswing Description: Shoots a fast, homing, wing-shaped projectile.
I have always been kind of ho-hum on Crossbow. While it's core to the base Max Damage DPS build, you're not supposed to evolve it for max damage. That makes it kind of sad in my book.
Despite my sadness, it's still a B-tier weapon. You can start to evolve it once you get it to 4* Forge as the double Crosswing about doubles the damage, making me slightly happier.
You don't technically evolve it in most builds because the sheer number of arrow projectiles apply a massive amount of vulnerability. The vulnerability amp, from the jewel, nets your entire damage output higher than evolving the Crossbow.
So I have Crossbow B in early, mid, and late game normal and hard mode. They are B+ in Faction Wars and B in Dungeon, Arena, and Adventure.
They are lower priority, maybe C tier, in Hero Clash.
They are A- tier for Nightmare Mode because the 2* forge can freeze a surprising amount of horde. It also applies the Basilisk slow very efficiently, in the same way it does vulnerability. But I'd put them at F tier in Boss Brawl because there's only one boss to hit.
The 3* forge "Reinforced Grip" is a below-average global buff. It increases projectile speed by 2.5%.
Duplicator, Projectile Speed, Duration, and Cooldown dramatically improve the efficiency of Crossbow, but only cooldown improves Crosswing. Again, this is a negative for the evolution.
Crossbow evolves from Speed Tome, which does not synergize well in the game. You only evolve Crossbow at 4* forge to round out a random build.
