This card's effect is a Continuous Effect that does not target.
Previously Official Rulings
These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami. They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: 
For this card’s effect, the chosen attack target must still be legal. You cannot force a monster to attack directly if it normally cannot, or force a monster to attack a monster on its own side of the field.
The effect of "Patrician of Darkness" does not override the effects of "Marauding Captain", "The Legendary Fisherman", "Solar Flare Dragon", etc. You cannot choose an attack target prevented by the effects of these cards. Examples: You cannot choose "The Legendary Fisherman" as an attack target if "Umi" is on the field. You cannot choose another Warrior-Type monster as an attack target when you control "Marauding Captain".
"Inaba White Rabbit" must still attack your Life Points directly since it is not able to attack other monsters. You cannot force it to with this card’s effect.
If a monster has the optional effect of attacking directly, such as "Rainbow Flower", you may choose a monster as an attack [sic], or a direct attack.
Replays may occur as normal when this card is on the field. If, after the replay, "Patrician of Darkness" is still on the field and they choose to restart the attack, you will still choose the attack target with the effect of "Patrician of Darkness".
If you control "Patrician of Darkness" and "Lord of D." you may still choose Dragon-Type monsters on your side of the field as attack targets.