A new take on an easy infinite combo that I love deep in my heart. Umbral Mantle has so much combo potential it's actually surprising it doesn't find its way into more budget decks.

This is infinite Umbral Elves. First thing to mention is that the deck can function as a normal elf deck somewhat. We play a lot of fast, small, mana maker elves, some Lords, and some other payoffs. But that's only if we can't get one of our 2 combos off.

Combo one: Umbral Mantle equipped to one of our 10 combo creatures, Marwyn, the Nurturer, Elvish Archdruid or Viridian Joiner. If the mana tapping potential for any of these creatures gets to 4 mana, they can untap themselves with Umbral Mantle for 3 and net you mana. Not to mention it makes them infinitely big.
Viridian Joiner and Marwyn are better for this strategy as they tap equal to their power. If we are able to ever stick an Umbral mantle on either of them with only 3 more mana, they can untap themselves with Mantle, become 3 power, tap for 3 mana, untap again and go infinite, exponentially netting mana.
Elvish Archdruid requires at least 3 other elves on the field to combo off. Not difficult, but harder than the other two.

Combo two: Same concept as Umbral Mantle; Staff of Domination using it's untap target creature ability and it's own untap ability to go infinite if any of our creatures are able to tap for 5 total. Just one extra mana isn't bad for a backup to the main combo.

Staff of Domination is interesting in this deck as it's not only a classic wincon for infinite mana decks, but it itself combos with the deck. Infinite mana gets us infinite draws, life, taps and untaps, drawing us into another wincon Walking Ballista or Ezuri, Renegade Leader.

Genesis Wave can be used as a value card if we can't find combo. Everything except for Ezuri can be hit by X 3 and 6 mana is fairly easy for us to hit. It can also substitute for Staff to essentially draw our deck onto the board in one spell (although Ballista will instantly die).

Ezuri, Renegade Leader and Walking Ballista are the last wincons. Ezuri makes all the elves infinitely big and gives them trample and Ballista will just shoot down the opponent easy peasy.

Other cards are mana elves and card draw. Lots of consistency in this deck. 8 enablers, 10 creatures that combo with enablers, 13 payoffs for infinite mana not including infinite power and toughness from Umbral Mantle combo specifically.

If we whiff on combo we still have a lot of mana potential to use our more mana intensive cards like Ballista, Wave, Ezuri and Staff. And if all else fails, elf beats still win games.