Fantasy Court Intrigue Card Game

I was inspired to make a game about conflicts within the royal family and the court after reading the Amber series by Roger Zelazny. Before the beginning of the game the king has died without leaving a designated heir. Each player starts as one of the members of the royal family(Princes, the Queen, and the King's Brothers), an important member of the court(Chief General, Archmage, Archbishop, Important Nobles and the King's former advisor) or an outsider vying for control of the throne(Orcish Warlords, Barbarian Kings, Exiled Elven Princes, Renegade Wizards etc.) I am trying to make the game mainly for many players(4+) and include lots of player interaction including negotiating and combat as well as stealing cards and allowing assistance and to other players(playing cards during their turn to help them, giving them resources, etc.) The goal is for the game to feel somewhat like a cross between MTG and Diplomacy with several new ideas integrated. I am shooting for a simple, streamlined(60-90 minute play time would be ideal) and greatly replayable game with room for expansion and the possibility of scheming and planning for several turns.

The goal of the games is to attain control of the throne before the other players do by fulfilling on of several victory conditions that involve goals ranging from controlling the legitimate heir to the throne and enough of the greater nobles to set up a government under your control to gaining the support and military required for a Coup'd etat. I am trying to avoid the "circling vulture" effect where no one wants to be in the lead by making the possibility of a quick and decisive victory an attractive option with the proper planning and positioning.

I envision the game having 3 resources: Gold, Influence, and Magic. They will be used to play cards ranging from Characters and Holdings(territories/buildings) to action cards(secret missions, raids, and political maneuvers). The cards will probably be in several small decks that have set contents so players can pick which kind of cards they want. I will include mechanics for battles but i will keep it simple as the main focus is on the political maneuvering.

Since the game is focused on player interaction i thought a turn sequence like this would be the best:

1. Income: All players receive resources and cards equal to the appropriate income ratings they have on all cards they control. Certain cards will allow you to chose which deck to draw from but others only allow you to draw from a particular deck
2. Action: Starting with the 1st player(player order will probably switch to the right each turn) and going around to the right, each player plays 1 action, character, asset, or holding card and any number of event cards from their hand. Some cards will allow multiple actions to be chained together(like in dominion). There will also be actions that you can take from your cards in play instead of playing a card. This phase will be repeated several times but i have not decided whether it will be limited by a set number or merely by how many resources and cards you have.
3. End/Cleanup(or whatever you want to call it): Your basic end phase where you resolve special effects that occur in this phase etc. Also in this phase players will declare if they have completed one of the victory goals.

This will hopefully allow players to be constantly thinking, updating their strategy and negotiating because of the short wait between each players actions and the constantly changing situation.

Feedback and suggestions would be greatly appreciated as i am new to both the forums and designing games seriously (i have played around with game design for several years and read a fair amount about game design) . I am particularly interested as to whether this concept has ever been done well before and if so, which game you think did it well.