DirtyLiar
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You can't build anything, but the closest analogue is capturing dwellings on the way to or near a city and "boosting" the army's strength in this way.
I gave examples from Starcraft. Therefore, for example, I can't yet come up with an analogue of a rush through aggressive buildings.
I don't know, I don't really want to introduce rituals just for the sake of rituals. But if we're talking about a ritual that creates a fundamentally new tier or set of tiers, we can consider it. For example, a significant one-time boost to turn order or an instant summoning of reinforcements is a fundamental boost that qualitatively changes the situation, but passive bonuses to attack, defense, etc. are not.
Although, if it's a qualitative improvement (exchanging low-level units for high-level units), then maybe, maybe...
Boosting turn order for a rush is also an option.
Another idea is "technologies," that is, for example, gaining high-level summons and mana for them.
And I don't really like passive bonuses myself. Although, for example, if it's a very significant one-time bonus (Attention, sale! Only today and only now, sacrifice 100 goblins and get +50 to attack in the next battle! :D), then there are also options.
And if the ritual is available by default for all Orcs, then this infringes on the rights of those players who will not build goblins. In its current form (according to the schemes I proposed), building is good because no unit is mandatory.
However, this strongly pushes this class to play with goblins...