Talk:Project Image/@comment-49.180.79.201-20200127095052/@comment-81.53.48.249-20200213142517

Here's more from AD&D 2nd edition Player's Handbook, pages 166-169:

 Illusions  are creations that manipulate  light, color, shadow, sound, and sometimes even scent. Higher level illusions tap energy from other planes, and are actually quasi-real, being woven of extradimensional energies by the caster.

[...]

In many encounters, some party members will believe an illusion while others see it for what it really is. In these cases, revealing the truth to those deluded by the spell is not  a simple matter of telling them. The magic of the spell has seized their minds. Considered from their point of view, they see a horrible monster (or whatever) while a friend is telling them it isn't real. They know magic can affect people's minds, but whose mind has been affected in this case?

[...]

Illusions do have other limitations. The caster must maintain a show of reality at all  times when conducting an illusion. (If a squad of low-level fighters is created, the caster <span style="left: 138.869px; top: 791.994px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00099);">dictates their hits, misses, damage inflicted, apparent wounds, and so forth, and the <span style="left: 138.869px; top: 813.566px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00114);">referee decides whether the bounds of believability have been exceeded.) Maintaining an <span style="left: 138.869px; top: 834.752px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00226);">illusion normally requires concentration on the part of the caster, preventing him from <span style="left: 138.869px; top: 855.939px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.001);"> doing other things. Disturb him and the illusion vanishes. <span style="left: 157.359px; top: 877.126px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00102);"> Illusions are spells of trickery and deceit, not damage and destruction. Thus, illusions <span style="left: 138.869px; top: 898.312px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00108);"> cannot be used to cause real damage. When a creature is caught in the blast of an <span style="left: 138.869px; top: 919.884px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00107);"> illusionary fireball or struck by the claws of an illusionary troll, he thinks he takes <span style="left: 138.869px; top: 941.071px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00107);">damage. The DM should record the illusionary damage (but tell the player his character <span style="left: 138.869px; top: 962.258px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00104);"> has taken real damage). If the character takes enough damage to "die," he collapses in a <span style="left: 138.869px; top: 983.444px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00262);">faint. A system shock roll should be made for the character. (His mind, believing the <span style="left: 138.869px; top: 1004.63px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00107);">damage to be real, may cause his body to cease functioning!) If the character survives, he <span style="left: 138.869px; top: 1026.2px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.0009);">regains consciousness after 1d3 turns with his illusionary damage healed. In most cases, <span style="left: 138.869px; top: 1047.39px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00109);"> the character quickly realizes that it was all an illusion. <span style="left: 138.869px; top: 111.709px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00104);"> When an illusion creates a situation of inescapable death, such as a giant block dropping from the ceiling, all those believing the illusion must roll for system shock. If <span style="left: 138.869px; top: 132.895px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00113);"> they fail, they die--killed by the sheer terror of the situation. If they pass, they are allowed <span style="left: 138.869px; top: 154.467px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00096);"> a new saving throw with a +4 bonus. Those who pass recognize the illusion for what it is. <span style="left: 138.869px; top: 175.654px; font-size: 18.4902px; font-family: serif; transform: scaleX(1.00106);"> Those who fail faint for 1d3 turns.

Note: Concentration still allows slow movement and things that don't require focus. In D&D 5, spells do not require concentration unless explicitly mentioned, so you can cast one spell requiring concentration, and go on casting other spells that don't. I don't know if there exist some spells that require so much concentration that nothing else can be cast (Project Image would be a nice candidate in that case). I believe AD&D 2 is more strict on concentration, but it appears that Baldur's Gate 2 could be even more strict.