I've always wondered about what happens when a unit champion/character dies from a challenge; Does a rank-and-file model take his place immediately after he dies? Even if the character/champion has already attacked?
For example, a unit of 10 chaos warriors charges a unit of 20 clanrats with a naked chieftain.
The chaos warriors' unit champion challenges the unit, where the chieftain accepts.
We'll say due to bad rolling (or whatever happened), the chieftain does no wounds (at I6), and the chaos warrior unit champion manages to slay the chieftain (at I5).
Does a rank-and-file clanrat immediately take his place, as there would be a missing spot in the front rank? And would he get to attack at the next initiative step of 4?
Does this same rule apply to, for example, if a regular clanrat unit champion died in combat (a model who would go at the same initiative step as the clanrats)?