The combination of Starmie EX and Articuno EX is a dangerous one, specifically because Articuno can be used to attack benched Pokmon, while Starmie is a high-damage, high-health EX that doesnt require any elaborate energy combinations or work to build up its energy stock
Sporemound makes a Saproling each time a land enters the battlefield under your control
A 4-mana 1/1 looks weak, but this draws a surprising number of cards with relatively little effort, especially when paired with effects like Master Biomancer and Tribute to the World Tree
OP12 is quite strong for opening, especially at its current price level
By comparison, a card like Snooping Page doesn't need you to fill your deck with spells that trigger repartee: just triggering its ability a couple of times is enough to make the card good
Ruthless Sniper and Horror of the Broken Lands, Stoic Champion, can quickly deal lethal damage when you're cycling 10+ cards a turn