If you want to build around K'rrik specifically, however, you can use him to helm a very strong life manipulation deck or generically good combo or control deck
The AFR set really started a new trend by introducing multiple new Dragon cards for every color
Insufferable Balladeer is pretty much only useful in a dwarf deck, despite its goading ETB ability
Goblin Anarchomancer Goblin Anarchomancer is by far the best of the 2-mana Gruul cost reducing creatures
Generally, Wizards of the Coast knows what they are doing when they face Commander in a precon, and all of these are powerful enough to win you the game with Energy
6: Wave of Vitriol Wave of Vitriol is a card I always strongly consider for any green deck, but I rarely pull the trigger on it since I always love playing my own artifacts, enchantments, and nonbasic lands and dont really want to blow them up alongside everyone elses