Mastery 6/7 should be tied to missions instead of tokens.

Examples

Archmage Heimerdinger

As Heimerdinger...

• Across multiple victories, personally deal 15,000 damage to structures.
• In a victory, stun at least three champions with the same grenade.
• Across multiple victories, score 5 multikills without allied assistance.

Warden Bard

As Bard...

• In a victory, cancel somebody summoning Rift Herald with Tempered Fate.
• Across multiple victories, stun ten enemies traveling through magical journey.
• Across multiple victories, prevent 8 deaths using Tempered Fate.