In that format, it can be oppressive because its naturally cheap and can stop blockers from doing their work, or it can just get ahead on value when paired with strong ETB effects
Creatures : Qasali Pridemage, Krosan Tusker, Indrik Stomphowler, Deadwood Treefolk, Sakura-Tribe Elder, Shaman en-Kor, Trinket Mage, Ophidian, Nullmage Shepherd, Coalition Honor Guard, Standard Bearer, Mulldrifter Much like Ertai, Rubinia will likely aggravate your opponents who will justifiably try and destroy her, so Ive included Flagbearers here too, as well as Shaman en-Kor (who can help redirect any damage dealt to Rubinia)
Now resolve
The reason phasing is so confusing is because the way it works today is very different to how it did when it was first introduced in Mirage
Swamp is a Magic: The Gathering trading card from Kaladesh #257
But that ETB ability is out of this world, allowing the caster to give flashback to any instant or sorcery in their graveyard