Lines are quoted from the official notes; buff/nerf tags are auto-classified from the numbers and can be wrong. Covers the 14 most recent Dota 2 patches PatchMeter has fetched.
⇄adjustBone ChillWhen Ancient Apparition deals magic damage with his abilities, affected enemies are chilled for 4s, reducing their movespeed by 2% per stack. If the target is an enemy hero, debuff also reduces their Strength by 0.1 + 0.1 per 3 levels. Each instance stacks and has independent duration
▲buffBone ChillIncreases Base Strength Reduction by 0.3
⇄adjustCold FeetNow deals 20/40/60/80 damage per second
⇄adjustIce VortexNow deals 10/20/30/40 damage per second
⇄adjustIce VortexNow slows movement by 8%
▲buffChilling TouchMana Cost decreased from 45/50/55/60 to 35
✕removedChilling TouchAghanim's Scepter no longer reduces mana cost
⇄adjustIce BlastNow deals 12/24/36 damage per second
▼nerfTalentsLevel 15 Talent Cold Feet Break Distance decreased from +300 to +250