3 May 2019
Tezzeret himself doesn't have affinity for artifacts.
3 May 2019
If a spell has multiple instances of affinity, each applies.
3 May 2019
If there are any additional costs or cost increases that would apply to a spell with affinity, apply those before applying any cost reductions.
3 May 2019
Affinity can reduce only generic mana in a spell's cost. It can't reduce color requirements.
3 May 2019
Affinity doesn't change the spell's mana value. It changes only how much mana you pay to cast the spell.
3 May 2019
The cost reduction is set before you pay any of the spell's costs. Specifically, you could lock in a discount for an artifact you control and then sacrifice that artifact to activate a mana ability.
3 May 2019
Affinity for artifacts means "This spell costs {1} less for each artifact you control."
3 May 2019
In a Two-Headed Giant game, Tezzeret's first loyalty ability causes the opposing team to lose twice X life and you gain X life.