Concept:
Microscopic characters are useful for identifying leaf drugs.
Step 1: Adhatoda vasica is also known as Vasaka.
Step 2: Its leaf shows characteristic trichomes and cystoliths.
Step 3: Multicellular glandular trichomes and cystoliths act as diagnostic features.
Step 4: Resin ducts and absence of stomata are not the correct features.
\[
\boxed{\text{Multicellular glandular trichomes and cystoliths}}
\]