Runi count as normal max-level Legendary cards for the base production points, but only one Runi card can be used on each land plot and they provide a number of additional benefits to the plot which are listed below. These boosts should provide a huge amount of additional utility to Runi and should help heavily incentivize players to collect multiple Runi regardless of their traits and components.
Please note that Runi do not need to be locked in game (since they can't be) but must be staked on the Ethereum blockchain to your Hive account before they can be used on land. Staking them on land will not require any additional Ethereum transactions.

Production Boost

Runi will provide a 100% PP boost to the base production of the entire plot. This is equivalent to a Legendary Totem, and can be combined with a Legendary (or other rarity) Totem for even more increased benefits.

Runi Core

The Runi Core - the little ball component at the heart of each Runi - acts as a Power Source that is able to manifest not only the Runi, but also up to four other cards working with it on the same land plot. As a result, plots that have a Runi as one of the workers will not need to purchase a Power Source, and no DEC will need to be staked to power the Runi or the other cards working on the plot.
Plots that have both a Power Source and a Runi will be able to have an extra worker card, for a max of six workers instead of 5, which can provide a significant additional boost to production.

Combined Runi

Combined Runi (when available) will act as having multiple, max-level, Legendary cards in one card slot and will gain a base production multiplier for each additional Runi combined into the card.
The formula is [Sum of base PP of each combined Runi] * [# of Runi]. The base PP for each Runi will be 1,500 for a regular foil and 10,000 for a gold foil (which are the standard rates for regular and gold foil legendary cards). The base production and the multiplier will be capped at a combine level of 5. Any more than 5 Runi combined together will not provide any additional production. Please note that this only applies to the base production of the Runi and not the production boost which will remain at 100% for both single and combined Runi.