How to counter Io in Dota 2

Tethers Io to an allied unit, granting bonus movement speed to both. When Io restores health or mana, the tethered unit gains a portion of that amount. The tether breaks when the allied unit moves too far away, or Io cancels the tether. Tether slows enemies touching it.

Summon five particle spirits that dance in a circle around Io. If a particle collides with an enemy hero, it explodes, damaging all enemy units in an area around it. Creeps take minor damage from touching a particle spirit, but do not cause them to explode. When its duration ends, any remaining Spirits explode.

Io gains attack speed, spell amplification, and health regeneration based on max health. If Io is Tethered to an ally, that unit also gains any bonuses granted by Overcharge.

Sends the spirits closer to you. Can be toggled on and off.

Sends the spirits farther away from you. Can be toggled on and off.

Teleports Io and a tethered ally to any location. After the spell expires, Io and the tethered ally will return to their original location. Double-click to teleport to your team's base fountain.

Break the link to the tethered unit.

Io gains outgoing damage amplification the closer it is to full health, and Health Restoration and Healing Amplification the closer it is to zero health.