Definitions for sparse. Here are all the possible meanings and translations of the word sparse. Princeton's WordNet(5.00 / 1 vote)Rate this definition: sparse, thin(adj) not dense. a thin beard; trees were sparse.
In League of Legends, the wombo combo is often characterised as the chaining together of a number of high impact abilities, often area-of-effect crowd control, leading to massive damage and multiple kills.
The origin of the Wombo Combo comes from Super Smash Bros Melee, as you stated in the question, and it is defined as two players in the game chain together certain moves to highly damage and/or kill the enemy. The moves compliment each other and thus create a combo.