For purposes of Aegar, a permanent was dealt "excess damage" if "one or more sources ... together dealt"—
- "an amount of damage to [the] creature greater than lethal damage", or
- "an amount of damage to [the] planeswalker greater than that planeswalker's loyalty before the damage was dealt",
as the case may be (C.R. 120.10). The trample ability, however, changes how combat damage is assigned, not how it's dealt (review C.R. 702.19).