THE POPULOUS BIBLE
E.3 The range on spells
All spells in Populous can only get casted by the shaman. Each spell has its own range - you can see the range indicator when selecting a spell. Note that, the higher you shaman stands (higher terrain), the more range. Shamans in towers also improve their spell range. So, to have the maximum range possible, you should move your shaman to inside a tower that is placed on a hill.
Let's see the range of the spells, by alphabetic order:
Angel of Death - 3072 range.
Armageddon - 3072 range.
Blast - 3072 range.
Bloodlust - 4096 range.
Convert - 8192 range.
Earthquake - 4096 range.
Erode - 4096 range.
Firestorm - 4096 range.
Flatten - 4096 range.
Ghost army - 4096 range.
Hypno - 4096 range.
Invisibility - 4096 range.
Landbridge - 5120 range.
Lightning - 6144 range.
Magical Shield - 4096 range.
Swamp - 4096 range.
Swarm - 6144 range.
Teleport - infinite range.
Tornado - 4096 range.
Volcano - 3072 range.
Source: Populous constant file.
In this image you can see the range indicator of the spell firestorm (4096 range).