Giving your Garruk protection from Dreadbore can be game winning
Original fearsome Dinosaur commander Gishath, Suns Avatar makes a great default choice, hitting the battlefield with haste and quite likely crashing through and finding even more Dinosaurs
And, depending on your other cards, he can be questing quietly while your opponent pays attention to something more threatening
Each spell with tiered has a base cost as well as multiple modes, each with their own additional costs
The only commander deck missing from Amazon's pre-order options at the time of typing this is the one themed after Final Fantasy 7 with Cloud leading the charge
So if you can give a creature unblockable, or go wide enough, there isn't much your opponent will be able to do