Since it takes so many counterspells, removal spells, and planeswalkers to keep the game in check, there often isnt much space in the deck for creatures
Here are some decks you can use in Heart of the Underdog: Crusady Crusadia is an Link Monsters archetype, and is related to the World Legacy archetype
Maybe not choice #1, but if you want to play off the top, the original can get you there
(Dont apply Weakness and Resistance for Benched Pokmon.) Farigiraf CC - Medium Rumble 40x This attack does 40 damage for each Stage 1 Pokmon you have in play
Call to the Kindred seems like the perfect fit for a deck like this provided you can make it around to your next turn with it still enchanting one of your Slivers
If you gain an amount of life "for each" of something, that life is gained as one event and the ability triggers only once