In the often-play category, we have Spikefield Hazard and Akoum Warrior
The last ability of Clive's Hideaway will allow you to cast both exiled cards without paying their mana costs (assuming you control four or more legendary creatures at that time.) In a Two-Headed Giant game, Traveling Chocobo's second ability does not affect triggered abilities of permanents your teammate controls
Thus, we get a land that generates two white, a blue, and a green, with absolutely no drawback
6 Hypergenesis If youre looking for an easy way to help everyone cheat in a bunch of creatures, lands, artifacts, or enchantments, then Hypergenesis is the way to go
Graveyard Marshal Graveyard Marshal looks to be a solid two-drop for all sorts of black decks moving forward and not just Zombie decks, although it will certainly see play in the latter
Humans you control gain haste until end of turn