Some cards give you energy counters, usually on resolution, but some cards add energy during other phases as a static ability, attack triggers, damage triggers, and activated abilities
The Saga starts by turning one of their noncreature artifacts into a 0/4 Wall, just a little bigger than the Dinosaur token you get the next turn
As a young boy, Jenson was attacked by Dihada's evil forces
While it doesn't copy mana abilities, there are so many powerful effects you'd want to trigger twice this restriction will hardly matter
Dragonhawk, Fate's Tempest Three generic, two red legendary creature Bird Dragon 5/5 Mythic Rare Flying Whenever Dragonhawk enters or attacks, exile the top X cards of your library, where X is the number of creatures you control with power 4 or greater
702.164b: Some rules and effects refer to a creatures total toxic value. A creatures total toxic value is the sum of all N values of toxic abilities that creature has