Can magic drain be chained to shrink if it was played during the damage step?

Yes, you can. Counter Traps can be played during the Damage Step.

are u sure, i lvl 3 judge to write that down cause i believe that only magic and trap that lower or higher the attack or defense of a monster can be played on the damage step

Counter traps can be used in the damage step, this is a fact.

From UDE's site, on the basic gameplay faq, near the bottom of the page:
http://www.upperdeckentertainment.co...y/default.aspx

THE BATTLE PHASE
If you do not wish to make any attacks, you may skip your Battle Phase and go straight to your End Phase.
It is important to understand the Battle Step and Damage Step, and which cards can be used during each part. (See pages 28-32 of the Official Rulebook version 6.0)

Spell / Trap Cards
Remember that Quick-Play Spell Cards & Trap Cards can be activated during the Battle Phase, but they cannot be activated during the Damage Step unless they specifically modify ATK or DEF ("Reinforcements", "Castle Walls", "Rush Recklessly", "Mirror Wall", "Limiter Removal", etc are OK and can be activated during the Damage Step. "Waboku", "Reverse Trap", "Mirror Force", "Magic Cylinder", "Imperial Order", etc. are not OK and cannot be activated during the Damage Step.)

Counter-Trap cards may be used during the Damage Step to negate an appropriate card. You can use "Magic Jammer" against "Rush Recklessly", for example, or "Seven Tools of the Bandit" against "Reinforcements".

Oh really!

Yes.
I was actually wondering about this for a while now.
So good

The old "rule" that only effects that modify atk/def can be used in the damage step was an oversimplified generalization that was actually NEVER correct. think about it flip effects have always worked in the damage step haven't they.

Basically the damage step is actually a series of substeps, and each substep has different effects that can be used in them.

the "only atk/def modifiers" rule only applies to the Damage Calculations substep (after flipping the monster, before doing damage, this is when you use atk modifiers).

then when damage is actually done to lifepoints, effects that trigger from damage form a chain (like don zaluug, and robbin goblin).

then is the "resolve effects" substep when flip effects are applied as well as effects that activate "after damage calculations" (like dd warrior lady).

then the send monsters to the graveyard step, when monster destroyed in battle go to the graveyard, and trigger effects can work (like sangan).

finally, I believe effects that say "at the end of the damage step" (like legendary jujitsu master) then activate after everything else is done right before leaving the damage step.

Also counter traps and multi-trigger effect monsters whose effects negate things (like horus LV8, and ryu senshi) are also allowed to be activated at any time to negate an appropriate effects.