Massmorph

When this spell is cast upon willing creatures of man-size or smaller, up to 10 such creatures per level of experience of the magic-user can be made to appear as normal trees of any sort. 

Thus, a company of creatures can be made to appear as a copse, grove, or orchard. Furthermore, these massmorphed creatures can be passed through — and even touched — by other creatures without revealing the illusion. Note, however, that blows to the creature-trees will reveal their nature, as damage will be sustained by the creatures struck and blood will be seen. 

Creatures massmorphed must be within the spell's area of effect. Unwilling creatures are not affected. 

The spell persists until the caster commands it to cease or until a dispel magic is cast upon the creatures. 

The material component of this spell is a handful of bark chips.

Except as noted above, this spell is the same as the fourth level magic-user spell, massmorph (q.v.).