Edit: woops, code parts got mangled a bit. Copy+paste them into notepad and use a fixed-width font (such as Courier) to display correctly

It's been a while so take what I say with some caution.

If you want a spell to affect another one (for example, Improved Renew affects all Renew spells but not other spells), you need to:

• set the SpellFamilyName (aka SpellClassSet) to the same value for both (maybe not?)
• set the SpellFamilyFlags (aka SpellClassMask) in the AFFECTED spell (Renew in this case)
• set the EffectSpellClassMasks in the AFFECTING spell (Improved Renew in this case)

The SpellFamilyName is just the identifier of the class that has the spells. SpellFamilyFlags and EffectSpellClassMasks are a bitmasking system. To better understand, turn the values in both into binary.

Renew rank 1 (Id=139) has the following SpellFamilyFlags by default, first in hex and below it the same value represented in binary (the exact name of the field may differ, I'm looking at the fields in Stoneharry's spell editor/accompanying database):
Id     SpellName0     SpellFamilyFlags     SpellFamilyFlags1     SpellFamilyFlags2
139    Renew          0x40                 0x0                   0x400
                      0000 0000 0100 0000  0                     0000 0100 0000 0000

Improved Renew rank 1 (Id=14908) has the following EffectSpellClassMasks for effect 1 by default, again first in hex and below it in binary. Imp Renew only has one effect (out of a possible 3), so the other two effects' EffectSpellClassMask (B1, B2, B3, C1, C2, C3) fields are left out:
Id     SpellName0     EffectSpellClassMaskA1 EffectSpellClassMaskA2 EffectSpellClassMaskA3
14908  Improved Renew 0x40                   0x0                     0x0
                      0000 0000 0100 0000    0                       0

Because Renew has the 7th bit set in SpellFamilyFlags, and Imp Renew has the 7th bit set in EffectSpellClassMaskA1, Imp Renew affects Renew.

If the bit was set in the second flags field for Renew instead, it wouldn't work.
SpellFamilyFlags is checked by EffectSpellClassMaskA1, EffectSpellClassMaskB1, EffectSpellClassMaskC1
SpellFamilyFlags1 is checked by EffectSpellClassMaskA2, EffectSpellClassMaskB2, EffectSpellClassMaskC2
SpellFamilyFlags2 is checked by EffectSpellClassMaskA3, EffectSpellClassMaskB3, EffectSpellClassMaskC3

It doesn't matter if Renew has a bit set set that Imp Renew doesn't match. So long as a single bit in a corresponding field is set, then the spell is affected.
If Imp Renew has a bit set that Renew doesn't have, that just means Imp Renew might affect other spells.
If Renew has a bit set that Imp Renew doesn't have, that just means Renew might be affected by other spells.


As an experiment, we can make the talent Shadow Reach affect Renew by adding a bit to Renew's flags that Shadow Reach already matches. Doing it this way is likely to have side effects. The "cleaner" way would be to take a bit that's unused among priest spells (in any of the SpellFamilyFlags fields), and set that in both the AFFECTING and AFFECTED spells.

We'll look at Shadow Reach rank 2 (Id=17323) because I can't find rank 3 for some reason. Again, it only has 1 effect:
Id     EffectSpellClassMaskA1               EffectSpellClassMaskA2         EffectSpellClassMaskA3
17323  0x682A004                            0x300502                       0x2040
       0110 1000 0010 1010 0000 0000 0100   0011 0000 0000 0101 0000 0010  0010 0000 0100 0000

If we set any of these bits in Renew's flags (in the appropriate field), Renew should have its range extended by 13%.

So I'll just open Stoneharry's spell editor, make a duplicate of Renew, set any of the bits from Shadow Reach's masks in an appropriate flags field of Renew, save and export the modified Spell.DBC, then copy it over to the server's DBC directory, put it in a client-side patch so I can learn the new spell, learn the original Renew and the modified version, then learn Shadow Reach (rank shouldn't matter, come to think of it, since all ranks affect identical spells).

As you can see, there were some side effects besides the increased range (the heal is stronger and costs less mana). Presumably because the bit by which I allowed Renew to be targeted by Shadow Reach is also targeted by other spells that have that effect.


Tips: use as few bits as possible. Depending on where you look, flags/masks will be in hex, binary or decimal. Use online converters.

It doesn't matter if I modify the files or not, it gives the same error.

You might be modifying an outdated version of the interface file. Think you want the one from patch-xxXX-2.MPQ

I couldn't get GameTooltip:SetSpellByID(ID) to work, so I used a hacky way to populate the gametooltip from a spell hyperlink. The only downside is that if you have a hyperlink popup on screen (the little box that appears when you click a chat link for a spell/talent/item), the popup will disappear.

If anyone knows how to actually get GameTooltip:SetSpellByID to work instead of resorting to ghetto magic, please let us know!


local AIO = AIO or require("AIO")
AIO.AddAddon()


if not AIO.IsServer() then
-- Hacky way to set up custom talent tooltips. Creates and reads an ItemRefTooltip from a spellID and returns a table of text with color and wrap data.
-- The ItemRefTooltip is shown, read and hidden again without ever appearing on the screen (hopefully)
local function GetSpellTooltip(spellID)
if (not ItemRefTooltip:IsVisible()) then
ItemRefTooltip:SetOwner(UIParent, "ANCHOR_PRESERVE");
end
ItemRefTooltip:ClearLines();
local linky = "124cff71d5ff124Hspell:"..spellID.."124h124h124r"
ItemRefTooltip:SetHyperlink(linky)

local numLines = ItemRefTooltip:NumLines();
local tmp = {};
local i = 1;

for currentLine=1, numLines do
local line = {};
local left = _G["ItemRefTooltipTextLeft"..currentLine];
local right = _G["ItemRefTooltipTextRight"..currentLine];

if ( left ) then
line.w = left:CanWordWrap();
line.leftR, line.leftG, line.leftB = left:GetTextColor();
line.left = left:GetText();
end
if ( right ) then
line.rightR, line.rightG, line.rightB = right:GetTextColor();
line.right = right:GetText();
end

tmp[i] = line;
i = i + 1;
end

HideUIPanel(ItemRefTooltip);
return(tmp)
end


function GameTooltip:ActuallySetSpellByID(spellID)
local tmp = GetSpellTooltip(spellID)

GameTooltip:ClearLines()
for i=1, #tmp do
if ( tmp[i].left and tmp[i].right ) then
GameTooltip:AddDoubleLine(tmp[i].left, tmp[i].right, tmp[i].leftR, tmp[i].leftG, tmp[i].leftB, tmp[i].rightR, tmp[i].rightG, tmp[i].rightB);
elseif ( tmp[i].left ) then
GameTooltip:AddLine(tmp[i].left, tmp[i].leftR, tmp[i].leftG, tmp[i].leftB, tmp[i].w);
elseif ( tmp[i].right ) then
GameTooltip:AddDoubleLine("", tmp[i].right, 0, 0, 0, tmp[i].rightR, tmp[i].rightG, tmp[i].rightB);
end
end

GameTooltip:Show()
end

end


To test it, enter the game, mouse over a spell in your spellbook and paste this in chat to set the tooltip to Blizzard rank 1:
/run GameTooltip:ActuallySetSpellByID(10)

I have not succeeded. I have just the base map ... :/

Do you get something vastly different from what's seen in this tutorial: http://modcraft.io/viewtopic.php?f=21&t=1686 ?

What you see is what you get. It's a template.

Man, that guide should really use layer masks more.

How are you going to access SpellFlyout.dbc?

To add a custom tooltip line for Epic difficulty items, you need to make some changes to Wow.exe (or alternatively do some Lua tooltip modding).

This is for WotLK 3.3.5 12340

Backup your Wow.exe.

Also, this probably requires that you've already patched Wow.exe to load custom interface files.

Open up notepad and copy this over:
OFFSET_1 =
OFFSET_2 =
OFFSET_3 =
OFFSET_4 =
OFFSET_5 =
OFFSET_6 =

Open Wow.exe in OllyDbg.
Right click, search for -> All referenced strings
In the strings window, hit ctrl+f and find "ITEM_HEROIC".
Double click it and it'll take you to something that looks like this (the addresses might be slightly different):
00627BA3      F641 18 08               TEST BYTE PTR DS:[ECX+18],08
00627BA7      74 24                    JE SHORT 00627BCD
00627BA9  |> /56                       PUSH ESI
00627BAA  |. |6A FF                    PUSH -1
00627BAC  |. |68 4866A200              PUSH OFFSET 00A26648         ; ASCII "ITEM_HEROIC"
00627BB1  |> |E8 8A211F00              CALL 00819D40
00627BB6  |. |83C4 0C                  ADD ESP,0C
00627BB9  |. |56                       PUSH ESI
00627BBA  |. |68 402DAD00              PUSH OFFSET 00AD2D40
00627BBF  |. |68 402DAD00              PUSH OFFSET 00AD2D40
00627BC4  |> |56                       PUSH ESI
00627BC5  |. |50                       PUSH EAX
00627BC6  |> |8BCF                     MOV ECX,EDI
00627BC8  |. |E8 F382FFFF              CALL 0061FEC0              ; Wow.0061FEC0
00627BCD  |> |3975 F0                  CMP DWORD PTR SS:[EBP-10],ESI
Right click the first "PUSH ESI" line (2 higher than the line with the ASCII comment), Edit->Copy address
Paste the address after OFFSET_1 in Notepad
Do the same for "CALL 00819D40" as OFFSET_2
Do the same for "CMP DWORD PTR SS:[EBP-10],ESI" as OFFSET_3

Now scroll to the bottom where you just see a bunch of lines that say "DB 00" (you can press Page Up/Down to advance one page at a time).
Pick a nice empty spot with 60 empty bytes. I chose 009DE3C0
Write down the address you choose as OFFSET_4
Calculate OFFSET_4 + 0x13 (http://www.miniwebtool.com/hex-calculator/), write it down as OFFSET_5.
Calculate OFFSET_4 + 0x24, write it down as OFFSET_6
Starting at your OFFSET_4, enter these lines, replacing OFFSET_# with your addresses:
TEST BYTE PTR DS:[ECX+18],01
JE SHORT OFFSET_5
PUSH ESI
PUSH -1
PUSH OFFSET_6
JMP OFFSET_2
TEST BYTE PTR DS:[ECX+18],08
JE OFFSET_3
JMP OFFSET_1

Press ctrl+G and go to OFFSET_6.
Right click the highlighted line, go to Edit -> Binary edit
Put your cursor at the leftmost place in the HEX field, right click and paste this (make sure "Keep size" is UNCHECKED):
49 54 45 4D 5F 48 45 52 4F 49 43 5F 45 50 49 43
5F 43 55 53 54 4F 4D 00 00 00 00

This will turn into ASCII "ITEM_HEROIC_EPIC_CUSTOM", which will be the name of our global Lua variable that holds the string we want to show in the tooltip.

Select all the red lines, right click -> Edit -> Copy to executable.
Don't close the popup, minimize it or drag it to the side so you can still find it.

Go back to the main window.
Press ctrl+G and go to OFFSET_1.
Select the two lines above it that say "TEST..." and "JE SHORT..."
Right click, Edit->Fill with NOPs
Then, with the red NOP lines still selected press space to edit them to:
JMP OFFSET_4
NOP

Select these 2 red lines, right click -> Edit -> Copy to executable.

Now go to the popup from before, right click -> Save to file...
Choose a name you'll recognize, like Wow_tooltip_test.exe.
Close OllyDbg.

Next you just need to add a string for ITEM_HEROIC_EPIC_CUSTOM to GlobalStrings.lua

Extract the most up-to-date GobalStrings.lua from your game archives (or if you've already modified it, grab your modified one).
Open GlobalStrings.lua, search for "ITEM_HEROIC_EPIC".
Under it, add this line, replacing the string with whatever you like
ITEM_HEROIC_EPIC_CUSTOM = "Epic Dungeon loot";

Save and pack into a custom MPQ or load it straight from WowInterfaceFrameXML

Finally, to create an item with this new tooltip line, set the 0x01 flag for the item in world.item_template.
If you're changing an existing item, remember to delete your client cache (WowcacheWDB).

If you don't know how to change the flag properly, take the old "flags" value from your world.item_template item row, convert to hex, add 0x01, convert back to decimal and enter it back into your database.

A warning is due, though. The 0x01 flag isn't used and its purpose is unknown, but it's possible that it will interfere with something. If the mod works but it crashes at a (random?) point, or has some other weird behavior, let me know. If this happens and you want to try to fix it, check documentation for the "flags" field in world.item_template and see which other flags are unused. You'll need to modify the condition we added for the 0x01 flag and update item flags.

Here's the result:

There's already spells you can cast while mounted, like paladin auras, warrior stances, dk presences, hunter tracking.

https://wowdev.wiki/Spell.dbc/Attributes
SPELL_ATTR0_CASTABLE_WHILE_MOUNTED           = 0x01000000, // 24 castable while mounted
Stoneharry's spell editor recommended for editing ease, you can just click a checkbox for it.