Here are some of my ideas:

TRIBE CAPTAINS

A variety of "Tribe Captain" units that can be trained and dispatched with Tribe Assignments. Several varieties could exist, and each variety utilizes a Tribe Technology, each tech having a small level up system. Some are one-off, consumable units, and some may fight in battles and either survive or not. Only one Tribe Captain can be dispatched at a time. Training Captain Technologies requires resources, and so does creating a Captain.

1. A SABOTEUR could be sent ahead of an assignment to arrive just before the troops as the first unit. The Saboteur would detonate explosives on the gate or otherwise sabotage it, dealing gate damage and thus reducing the amount of time the defending Stronghold's tribe has to respond and garrison. Consumable. Damage scales with Saboteur technology level.

2. A BANDIT LORD could be dispatched with an assignment to provide troops with Silent Travel for a period of time. Silent Travel is an effect that allows troops in an assignment to move without notifying the target tribe of an incoming attack. Not consumed. May be killed in battle. Percentage of time considered Silent Travel scales with Silent Travel technology level.

3. A SHAMAN could be dispatched with an assignment to cast the Confusion ability during battle. Confusion is an ability that nullifies the advantages of enemy (and allied?) Blacksmiths and Armories for a set number of turns (not rounds) distributed randomly throughout a given round. Not consumed. May be killed in battle. Percentage chance of a given turn being affected by Confusion and the number of rounds (not turns) affected by Confusion increased with Confusion technology skill level.

4. A WARLORD could be dispatched with an assignment to cast the Battle Cry ability during battle. Battle Cry is an ability that adds a multiplicative modifier to all Blacksmith and Armory buffs held by troops in an assignment. Also prevents Confusion from taking effect. Not consumed. May be killed in battle. Active only during the first round of a battle. Modifier increased by levels toward the Battle Cry technology.

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TRIBE BANNERS

Tribe Banners are structures that can be built on occupied Strongholds which provide a passive, area of effect buff to allied units engaging in combat within it's range. Area of effect would be displayed as a faint aura on the minimap (replacing slaren's map and really reducing the need for it as an indicator of map control). Several varieties would exist, but only one may be placed on a given Stronghold at a time. When a Bannered Stronghold is captured, the Tribe Banner is destroyed. Banners are limited duration and expire after a period of time. They are meant to be strategic use, not persistent. Banners can be leveled up to increase their effects. Placing a banner costs resources, and so does leveling.

1. TRIBE BANNER OF PRIDE when erected on a controlled Stronghold provides a tribe with VPR gain. Without this banner, VPR gain is halted. Free to place. Cannot be upgraded. credit to Dark for the idea

2. TRIBE BANNER OF HASTEFUL SIEGE would provide a movement speed bonus to units on an offensive assignment while within the area of effect.

3. TRIBE BANNER OF RAPID RESPONSE would provide a movement speed bonus to units defending the affected Stronghold regardless of distance; assignment not necessary.

4. TRIBE BANNER OF VIGILANT WATCH would provide the ability to view a portion of the contents of incoming attacks before they reach the gate.

5. TRIBE BANNER OF VICIOUS SLAUGHTER would provide all units on a defensive assignment with a percentage additional attack damage at the cost of health.

6. TRIBE BANNER OF STALWART DEFENSE would provide all units on a defensive assignment with a percentage additional health at the cost of attack damage.

7. TRIBE BANNER OF RATIONED MEALS would reduce the upkeep of all units stationed in a Stronghold. credit to giu for mentioning this idea while talking to me a minute ago

Well, that's what I've got for now. What do you all think? What other perks can you think of?

EDIT: Dark had a great idea in tribe chat just now. Banner of Pride adds some depth to the system, making Strongholds more like outposts. Maybe it'd be appropriate to have more of them, closer together? Durations of the various banners would need to vary to balance things. This is all very interesting.