Say your opponent's saved at least one removal spell, this tends to push your required mana closer to 9 before you start any trouble
Mewtwo ex is a Basic Pokemon and only requires two energy to deal 50 damage with the move, Psychic Sphere
If you can whittle away their other attackers and leave them with just one creature left attacking, you can cast Blessed Alliance to take that last attacker out
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Since it's an instant, you simply pass your turn, wait until your opponent's upkeep, and then cast it, which is very close to getting an extra turn (the main difference is that your opponent will get to untap)
A soul tangled in dried grass, Bramblin has 40 health points and can use the ability Ride the Wind, which enables players to flip a coin to switch it immediately with a benched Pokmon: thereby removing the retreat cost