Looks very cool, but to me the portal upgrade path seems to peak at level 2 and get potentially worse at level 3 (ie. if it spawned 10 felhounds over 10 seconds that is only equal to level 1, which had done it all at once).
So they are different flavors, which seems to be how you've phrased it, but in WarCraft 3 it is not standard practice to have an ability which uses levels to do evolutionary changes.