William One Eye made an interesting Banana Party suggestion which got me thinking about this suggestion:

[EDIT: I made some changes based on the discussion so far.]

Name: Natural Disaster
Rarity: Legendary
Type: cast on a port
Duration: 24 hours
Turn Cost: 24
Description: Destroys 5% of a port's current stock of goods to sell [EDIT: and 2% of all player warehouse goods] excluding gold bars. Then for the remaining duration of the curse the port pays +3 gold for each resource (except gold bars) sold by any player to this port [EDIT: by fleets only, not sold from player warehouses].
The target port has an easily visible message on the map and the market page saying "Repairing Flood Damage! 8:28:37 remaining"

Crafting cost:
10x Flood
3x Hostile Waters
1x Tidal Wave [EDIT: 5x tidal wave]
2x Voodoo Storm
4x Swarm of Worms
[EDIT: 1x Call Leviathan]
Crafting duration: 48 hours

Flavor Text: Your Master Witch Doctor has crafted a powerful spell capable of unleashing a massive tidal wave on an unsuspecting port. The inhabitants will never know what hit them while you can take advantage of their sudden need to buy your trade goods.
"Good things come to those who... cast voodoo at unsuspecting NPCs"

"Party Card Routes" dominate the strategies of large traders. This card specifically doesn't help Party Routes but instead encourages more diverse trading strategies.
Use this in combination with my other suggestion "Incite a Riot" to lure unsuspecting traders to a certain port and then plunder them.

Please use the poll at the top of this thread to cast your vote.

-Captain D

I would suggest Natural Disaster is probably reserved for use by admin, and since tidal wave is already been used,
perhaps Tsunami Would be a possible atlernative name

does this include player owned warehouses a disaster is quite blind to such details imo
what about port population or ships caught in the harbor? i have helped in tzunami relief work, more than lost supplies it is people and the infrastructure to produce goods that's gone.

Arson, is a different story, some misguided pirate who sets certain (port owned) warehouses on fire. no need for the above questions then.

however, is this card merely a general trade related card or should it have some sting in it as well? that is what my initial questions a re about.

even when it is purely trade related i like the idea to manipulate the price of ports (especially on the day when the new prices will be determined . it could lower the value of the other ports dramatically since they are the more expensive ones to do trade with

Best use of this is to have a high leveled warehouse, and store it up with a lot of random goods, and cast this, as the duration at being only 24 hours, the caster wouldn't get a lot out of it using just normal trading.

How about we X4 the duration, X2 the cost, and X3 the craft time.

I made edits to my original suggestion based on the feedback so far.
I made the cost a bit higher and added 2% destruction of player warehouse goods. Also only fleets get the bonus, not warehouse sales.

-Captain D

I still think the duration is too short, as the caster would cast so he can gain more gold, or to help his guild mates earn money.

To gain more gold, I am just gonna take the average, one can ship per day (24 hours), 250000?

Bonus of 1.5 mill, which is not a lot considering that this has a high cost.

To help his guild mates, makes sense, but the guild mates would have to have their fleets transport to that port too.

A 4xLM+cutter fleet can carry 6,000 crates out of a port per day. A +3 buy price on each crate would equate to +18k daily profit per fleet. A large player with 100 fleets would see a total daily profit increase of +1.8M. That is not a significant amount for 1 large player. The real advantage would be telling your guild to prepare so that maybe 500 guild fleets trade in the port during the duration and make 9M more gold than usual.

After doing this math I'm thinking the +3 buy price isn't enough to make it worth crafting for 48 hours. +9M gold for 500 fleets is not nearly as much as the materials and the bother of organizing a guild's trade routes.

Maybe it should be a %-based increase? Not sure how much though.

-Captain D