BurningPyro

When Dendro meets Pyro, it triggers Burning, which continuously deals Pyro DMG until it wears off.

BloomHydro

When creatures are affected by Hydro and Dendro, the Bloom reaction will be triggered, creating Dendro Cores.

CatalyzeElectro

When creatures are affected by Electro and Dendro, Quicken will occur, which will render them Quickened.