I have a Lazav, the Multifarious in play, and a Fresh-Faced Recruit and an Affectionate Indrik in my graveyard.
I attack with Lazav, and my opponent blocks with a Nullhide Ferox. I pay two to turn him into a copy of the Recruit, who has first strike because it's my turn; I deal two first strike damage; then pay six to turn Lazav into the Indrik. Does Lazav deal regular combat damage as well? Do I kill the Ferox?
In this scenario, unless Lazav has double strike, Lazav won't assign combat damage during the second combat damage step, even if it didn't have first strike by then, since it "had ... first strike ... as the first combat damage step began" (C.R. 702.7b).
Unless a creature has Double Strike, it simply can't deal damage twice. First Strike shenanigans don't work.
Rule 510.4: (…) The only creatures that assign combat damage in [the 'regular' damage step] are the remaining attackers and blockers that had neither first strike nor double strike [during 'first strike' damage step], as well as the remaining attackers and blockers that currently have double strike. (…)
I attack with Lazav, and my opponent blocks with a Nullhide Ferox. I pay two to turn him into a copy of the Recruit, who has first strike because it's my turn; I deal two first strike damage; then pay six to turn Lazav into the Indrik. Does Lazav deal regular combat damage as well? Do I kill the Ferox?
EDIT (Oct. 16): Correctness edit.
EDIT (Jul. 18, 2020): Edited.
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules