The locate city bomb is a series of metamagic feats you can apply to a the locate city spell to do high damage over a very wide area.
Typical process:
Cast locate city from Races of Destiny.
Use the Snowcasting feat from Frostburn to add the Cold descriptor to locate city.
Use the Flash Frost feat from Player’s Handbook II, which can only be applied to cold spells, to add 2 cold damage to all creatures within the area of the Snowcasted locate city.
Use the Energy Substitution feat from Complete Arcane, which can only be applied to a spell that deals acid, cold, electricity, or fire damage, to turn the cold damage to electricity damage.
Use the Born of the Three Thunders feat from Complete Arcane, which can only be applied to an area spell with the electricity or sonic descriptor that deals hit point damage. Among other things, this forces creatures within locate city’s area to make a Reflex save.
Use the Explosive Spell feat from Complete Arcane, which can only be applied to a cone-, cylinder-, line-, or burst-area spell that allows a Reflex save, to force those within who fail the Reflex save to the edge of the effect, taking 1d6 damage for every 10 feet moved.
If the locate city spell were banned, what other spells could use this combination of feats to produce a similar effect?
The locate city spell has a radius of 10 miles/level; I'd consider a spell to have a similar effect if its area of effect was also very large (and if the rest of the locate city feat stack worked with it).
(Context: https://rpg.stackexchange.com/a/159280/21179)
Best Answer
The rules are not good about defining “bursts” versus “emanations.” However, I am going to treat all ongoing effects “centered on you,” or that are otherwise mobile, as emanations, and therefore not bursts, and therefore not eligible for Explosive Spell. That dramatically narrows things down.
Likewise, any kind of instantaneous effect in a circle/sphere (the rules use the terms interchangeably) is a burst unless it specifically says otherwise. I’m also going to include spreads here—those are “like bursts,” and fireball uses one—and fireball is literally the example spell used in Explosive Spell’s description, so I suppose they must be OK.
When an effect has a duration, but doesn’t move, there is usually no difference between burst and emanation, and the rules almost never bother to define which something is. I will list these, but with an asterisk to highlight that you could argue/rule that they are emanations and therefore not allowed with Explosive Spell.
Those rules dramatically limit the list; as of this writing, I have found only three. I’ll also include locate city itself just for comparison.
Clearly, locate city is vastly superior to any other option, but these other options can still be heavily problematic.
While apocalypse from the sky works—and without needing Snowcasting, Flash Frost, or Energy Substitution, as it can deal sonic damage natively—as a 9th-level spell it almost doesn’t matter (Explosive Spell will still add vast amounts of damage to it, though—instead of 10d6 it will be many thousands of d6s). At lower levels, weather eye is the clear winner—far less area than apocalypse from the sky or locate city, but still quite large. The rest are smaller, much higher-level, and/or dubious targets for Explosive Spell.