Seismic Bond

1. Rank 0While a channeled Ability is active, Companion melee attacks create a 4m shockwave for 5% of their melee attack damage. Damage dealt by your Companion increases your Ability Efficiency by 0.5% for 2 seconds. Max 10 stacks.
2. Rank 1While a channeled Ability is active, Companion melee attacks create a 4m shockwave for 10% of their melee attack damage. Damage dealt by your Companion increases your Ability Efficiency by 1% for 4 seconds. Max 10 stacks.
3. Rank 2While a channeled Ability is active, Companion melee attacks create a 4m shockwave for 15% of their melee attack damage. Damage dealt by your Companion increases your Ability Efficiency by 1.5% for 6 seconds. Max 10 stacks.
4. Rank 3While a channeled Ability is active, Companion melee attacks create a 4m shockwave for 20% of their melee attack damage. Damage dealt by your Companion increases your Ability Efficiency by 2% for 8 seconds. Max 10 stacks.
5. Rank 4While a channeled Ability is active, Companion melee attacks create a 4m shockwave for 25% of their melee attack damage. Damage dealt by your Companion increases your Ability Efficiency by 2.5% for 10 seconds. Max 10 stacks.
6. Rank 5While a channeled Ability is active, Companion melee attacks create a 4m shockwave for 30% of their melee attack damage. Damage dealt by your Companion increases your Ability Efficiency by 3% for 12 seconds. Max 10 stacks.

Facts based on the Warframe Wiki (CC BY-NC-SA 3.0)