Natural Affinity by paying ({2} magic symbol) ({G} magic symbol) , causing all lands to become 2/2 creatures in addition to their other types.
Cast
Darkness Descends by paying ({2} magic symbol) ({B} magic symbol) ({B} magic symbol) , putting two -1/-1 counters on each creature.
Each land dies as a state-based action due to having 0 toughness, as well as each creature that had toughness 2 or less.
Necroskitter triggers for each creature and land your opponents controlled that died, returning them from their graveyards onto the battlefield under your control.
Notes
You can prevent your own creatures / lands from dying by also having an anthem effect that boosts their toughness on the battlefield.
Results
Gain control of all lands opponents control.
Gain control of some creatures opponents control.
Mass Land Denial.
Metadata
In 98 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Ruthless (Bracket 4+).