IV seems to give this card a little more oomph than Chandra, the Firebrand did, and Im pretty sure bloodrushing a Ghor-Clan Rampager on a Phoenix is one of the dictionary definitions of a BIG GAME (TM)
The creature card you return, if any, isn't a target of Black Sun's Twilight
Assuming youve got five mana the turn after Ojer Axonil is played, even if youve just got five spells that deal one damage each, suddenly youve got 20 damage in hand with nothing else needed
Finally, the deck features a handful of powerful removal spells and wrath effects, spells that can directly turn vehicles into artifact creatures (avoiding crew costs), spells that can protect your vehicles, as well as powerful card-draw engines such as Whirlwind of Thought and repeated token generators such as Outlaw's Merriment, Efficient Construction, Saheeli, and more
For most Cubes though, I love Walking Ballista as a solid card that can go in any deck that offers relevant support to artifact decks and stuff like delirium