Once you have a Hardened Scales and Ballista in play, always be on the lookout for ways to kill your opponent, as they are easier than you might think
Instant Color tag templates(None) Kuldotha Rebirth As an additional cost to cast this spell, sacrifice an artifact
Both also work well with the aforementioned Arbor Elf, allowing you to net even more mana by untapping the land these Auras are attached to
You dont gain life, draw a card, or get to play an additional land
Were already seeing Zendikar Rising experiment with using different card types as the front side of these, which will affect deck-building and combo options across various formats (the front side determines how you can search for or target these cards when they arent in play)
This comes up in the later stages of a draft, where your two primary colors are well-established