There are 3 steps to battles..
1. The battle step where trap / quick play spells may activate when an attack is declared.
2. The damage step where only certain quick play (affecting the atk/def) / counter traps / monster effects from hand (honest / kalut) may activate. This is also the time when a facedown monster (if attacked) is flipped.
3. The damage calculation where honest / kalut may be dropped. The only counter traps that can be activated here are the ones that negate monster effects (divine wrath / GB war chariot / Chivalry)
After all these are taken into consideration..the turn player ruling applies
Here're some scenarios
Player A uses Jain, Lightsworn Paladin to attack Player B's Shura
1. During battle step, Player B drops kalut in chain after Honest is dropped
- Shura gains 1400atk while Jain gains 3200atk due to honest resolving AFTER kalut
The battle will then proceed into damage step (where jain gains additional 300atk by its effect), followed by damage calculation
Result 1 (assuming nothing else occurs during the remaining 2 steps)
- Jain (5300atk) attacks Shura (3200atk) causing Player B to lose the difference and have shura destroyed.
2. During battle step, Player A passes the turn player to Player B who drops kalut. Player A then chains by dropping Honest from hand.
- Jain gains 1800atk (due to honest resolving BEFORE kalut) while Shura gains 1400atk
The battle will then proceed into damage step (where jain gains additional 300atk by its effect), followed by damage calculation
Result 2 (again, assuming nothing else occurs in next 2 steps)
- Jain (3900atk) attacks Shura (3200atk) causing Player B to lose the difference and have shura destroyed.
These are what can happen in the battle step, assuming again that no traps / spells get activated.
I'm lazy to type the rest but its pretty straightforward. =)
Just apply everything mentioned for the different steps.
Also, when playing, either player (regardless of attacking / defending) should ask your opponents before they do anything.
Some cards that cause situations like this:
Monsters :
Honest (ALL STEPS)
Kalut (ALL STEPS)
Quick Play Spells :
Limiter Removal (Battle and damage step)
Shrink (Battle and damage step)
Traps :
Mirror Force/magic cylinder/d.prision/ sakaretsu armor (Battle step only)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
There are actually more of the above but im lazy =P
Counter Traps (ALL STEPS) :
GB War Chariot
Divine Wrath
Divine punishment *you'll need sanc of the sky to use..DUH*
Chivalry
(Not sure if there're anymore)