The Avatar expansion even has 46 themes altogether, letting you mix scenes, characters, and elemental ideas from the show into different quick-play combos
The scry lands are fairly cheap and would be a great swap for some of the basics
Also, note that this is great in token matters decks like Jaheira, Friend of the Forest with a Red Background, where you can tap them for mana and keep them around for mana later
Kefkas ability to wear down your opponents while helping you keep a steady supply of new cards feels extremely relevant to the current midrange meta in cEDH, although Im not sure that he will outperform Tymna the Weaver // Kraum, Ludevics Opus
This doesnt come without a cost though, as Kaldra Compleat has a whopping 7 mana cost (both cast and equip), which is especially huge compared to the standard one to three mana that most equipment cards have
What are your decks that want these kinds of spells, and how well do they work