Filling the battlefield with Food, Rat, and Army tokens allows you to utilize more permanents as resources
Apart from pre-release events (which are designed to promote new products in a casually fun way rather than foster a healthy competitive environment), the oldest custom format was an experimental format known as Prop 15/3
resolve one of the triggers of the other Shifter, unmorph it, copy the Seer, draw 2 (4 total)
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.) Creature - Shade Color tag templates(None) Evolved Sleeper : This creature becomes a Human Cleric with base power and toughness 2/2
Some events, like Pokmons League Challenges, even let you earn points that could qualify you for bigger competitions like the World Championships
My love of the game's history as well as my recent dives into Classic Commander with its focus on older characters really fueled this, as pouring over those old legends often frustrates me