These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.05 s (backtrack: 0/20).

[ebuild  N     ] dev-games/irrlicht-mt-headers-1.9.0.13::gentoo  737 KiB
[ebuild  N     ] dev-games/irrlicht-mt-1.9.0.13::gentoo  0 KiB

Total: 2 packages (2 new), Size of downloads: 737 KiB