Yawgmoth's Will was the OG version and was played heavily in Storm decks, allowing you to replay all your rituals to increase your Storm count before killing your opponent with Tendrils of Agony
There have been decks in past formats that were so dependent on their stadiums that they didn't function without it
In the Booster Pack, two more Legendary cards are available, which provide Healing support and Tactical disruption: Espeon ex is a Psychic card
Vilis, Broker of Blood allows you to spend one black mana and 2 life to draw a card by targeting itself, which you can repeat eight times until Vilis poetically succumbs to their own ambition
During the prerelease I built a deck almost entirely around Toxic and it was honestly a blast
This condition prevents the affected Pokemon from attacking or retreating, leaving it stuck in the Active Spot with no action for one round