The charge for the stronger version is only available at level 25, so it can only be used in duels.
Hero - Hellspawn Envoy, level 12
Unit using gating - 32 Juggernauts.
Result of gating - 27 Juggernauts.
And after that, still complaining about gating? The summoned unit had already taken out half of the defenders by the time we broke through the gates!