Disgaea: Hour of Darkness/Geo Panels

This is a quick guide about Geo Panels within the game Disgaea: Hour of Darkness. I wrote it mostly on a whim, but I believe it to be fairly complete. Hopefully, I have explained what Geo Panels and Geo Symbols are, what they do, how to create chains, and any miscellaneous topics involved.

Note: anything marked VERIFY is something that I still need to check, and will hopefully update in the future.

Basics
Geo Panels are special rules that apply to specific regions of the map. There is an excellent introduction to Geo Panels in the third battle of the game; I would urge you to use it, as it will be much easier to see Geo Panels in action than to try to read about them. (On that battle, if you wish to set off a chain reaction to destroy all panels, move to the slightly raised panel a few steps from the Base Panel, and attack the Geo Symbol there.)

Colors
There are six colors of Geo Panel:
 * Red
 * 1) Green
 * 2) Blue
 * 3) Yellow
 * 4) Purple
 * 5) Cyan

And six colors of Geo Symbol:


 * 1) Null
 * Red
 * 1) Green
 * 2) Blue
 * 3) Yellow
 * 4) Purple

Outside of story battles, these are always created in order, so if there are, for example, 4 different colors of panel on the map, they will always be red, green, blue, and yellow.

Effects
The effects that a Geo Symbol can have: All of the Symbols whose names include numbers have their effects stacked; for example, you can have Ally Damage 120% or EXP +150% or ATK -100%. Opposite effects (ATK +50%, ATK -50%) do not stack directly.

Color Change and Destruction
There are a couple of good things that happen when Geo Panels are destroyed or change colors. First, all units standing on a Geo Panel when it changes colors (or is destroyed) are damaged. Second, the bonus meter goes up (rapidly). Third, when all Geo Panels are destroyed, an explosion which damages all enemies occurs.

Geo Panels change color when a Geo Symbol of a different color is destroyed on top of any panel of the same color.

Geo Panels are destroyed when the Null Geo Symbol is destroyed on top of any panel of the same color.

Neither color change nor destruction is instantaneous; panels are changed in a spiral outward from the place where the Geo Symbol was destroyed, and if multiple Geo Symbols are destroyed by one color change, their color changes occur in the order of their destruction.

Geo Symbols can be destroyed four different ways:


 * 1) They can be attacked and destroyed (if they are not Invulnerable).
 * 2) Damage from a color change will always destroy a Geo Panel.
 * 3) An enemy unit can be thrown onto the Geo Symbol.
 * 4) The Geo Symbol can be thrown onto an enemy unit.

Chains
Chaining the destruction of Geo Symbols is a very good thing which increases the damage dealt to units standing on the Panels and rapidly increases the bonus meter.

When a color change occurs, each panel that changes increases a counter in the upper left corner. The amount that each panel adds is equal to the number of times it has already changed color in the current chain, so the counter will go up much faster if you chain color changes. After the chain has completed, the bonus bar will fill according to how high the counter goes; each 100 on the counter equates to approximately one full bar, and destruction of all Geo Panels adds about one more full bar. (You do not have to destroy all Geo Symbols to get this bonus, only all panels.)

There are two requirements to be able to destroy all Geo Panels on a level. First, there must be at least as many Geo Symbols as colors of Geo Panel. Second, you have to be able to reach all Geo Symbols, or the ones you cannot reach must be placed so that you can destroy them as part of a chain.

The best (though not the only) way to clear all the Geo Panels on a level is to chain all the Geo Symbols. This will give you the maximum boost to the bonus meter, and usually makes it easy to get everything on the meter. If you want to do this, there can be no more than one 'No Color Change' symbol, and it cannot be the Null symbol.

Chain Strategies
Put all Geo Symbols except for one on a single color. If there is a color of panel with no corresponding symbol, make sure that is the color that all the Geo Symbols are on. Choose one of the Geo Symbols that you will destroy first, and place the Null symbol on that color. Then destroy the chosen symbol. This is similar to the first, except that the Null symbol is placed on the same color as all the other symbols. Just make sure that the Null symbol is the furthest symbol from the one that is destroyed first. This one is slightly more complicated. Start by placing two colored Geo Symbols on a single color of Geo Panel (one without a corresponding Geo Symbol, if possible). Choose one of them to destroy first, and put it at the start of your list, and put the other one next. For example, if you start with red and green on yellow, your list will start out like this: From here on, always place Geo Symbols such that they are on a panel the same colors as the Symbols two before them on the list. For example, the blue and Null Symbols might be placed like so: 
 * 1) Red on Yellow
 * 2) Green on Yellow
 * 1) Red on Yellow
 * 2) Green on Yellow
 * 3) Blue on Red
 * 4) Null on Green

Special Considerations for Chaining
There are three types of Geo Symbol which require special attention when setting up chains. They are: Invincibility is easily overcome: the only technique that does *not* work to destroy Invincible Symbols is directly attacking them. You can throw them into enemies, throw enemies into them, or use technique 3, above, and make sure that they are *not* on the first color of panel.
 * Invincibility
 * No Color Change
 * No Lifting

No Color Change can be tricky. It must *always* be the first Symbol in a chain. You can destroy all of the panels on a level even if you have two or more No Color Changes or the Null Symbol is No Color Change, but you have to do it in multiple chains.

No Lifting is tricky because it essentially glues all symbols (and enemies and allies) to whatever color it is sitting on. Usually, this just requires you to be careful about how you make your chain, but sometimes it is impossible (for example, if you have a No Lifting Symbol, all Symbols are on the same color of Panel, and the Null Symbol is in the middle). In this case, you can use certain special abilities (such as Triple Strike, Tiger Punch, Delta Kick) which move the enemy unit. It is preferable to use a weak unit to do this, as a strong unit may destroy the Symbol.

Geo Change
The 'Geo Change' ability of Scouts re-panels an area; this is very useful in the item world on occasion (example: a full level covered in No Lifting and Invincibility, with a Gatekeeper on a Dimensional Gate which is in the corner of a 2x2 island). Geo Change works even after all panels have been cleared, which is good when you don't quite get a high enough bonus from destroying all of the original Geo Symbols, or you screw up a long chain.

Miscellany
When a character is holding a Geo Symbol, that symbol has its effect on the color of Geo Panel the character is standing on.