You cant use it to pay for colored mana symbols like red or blue unless a card explicitly says you can spend it as any color.
Not the worst cards, just the cards with the most potential under the right circumstances
It seems like youll want to give Trelasarra lifelink so that she can power up herself, whether thats Basilisk Collar, Shadowspear, or True Conviction
Other MTG sets gave us more nonlegendary eldrazi options, like Breaker of Creation, Ulamog's Dreadsire, Sire of Seven Deaths, and Flayer of Loyalties to ramp into
Its ability to disrupt the opponent's Item plays also make Galvantula ex a high utility card that only got its price valued higher with its Special Illustration
In Generation VI, Salamence received a Mega Evolution but, while Mega Salamence's wings becoming a crescent moon looks awesome, the overall design isn't as strong as the original's