When Ogerpon changes its mask to the Wellspring mask, its type also changes to Water in its Terastallized state
A lot of factors go into determining the value of your cards, however, so you need to make sure you have a good idea of what to look for
The first is that no one has a maximum hand size anymore - not you, not your foes, no one
Metallic Rebuke : Instant, casting cost of two generic and one blue mana
Then, when Teferi's ProtectionTeferi's Protection was printed in Commander 2017 , it became the ultimate answer to any problem short of Thassa's OracleThassa's Oracle, although protection from everything was only a small part of the reason why
Knowing when to quest, when to challenge, when you use your actions, etc