Typically, it gets played for its cycling + madness cost ala Ichor Slick from TSP Limited and flashes back, but it has surprisingly high flexibility for such a good card (note that you cant buy it back when its being flashed back as it gets auto-exiled, but you can do things like cycling + madness + buyback if the game goes long)
Yet Fire Energy type Pokemon are also known for having some of the most powerful attacks in the game though this can sometimes come at a price, with Energy cards often lost when using the more devastating attacks that Fire type Pokemon have
If the land you played or spell you cast shares a mana value with multiple digits in the chosen number, cross only one of those digits out each time Duelists' Convocation International's last ability resolves
Enchantments can have static effects, triggered abilities, or even activated abilities, while sorceries simply do what they say on the card, like Strangle deals 3 damage to target creature or planeswalker, and then go to the graveyard
It basically refers to any and all lands that can produce two different types of mana
