A table cell specified that way belong to the previous row, so for terminating a row consisting of only "block" cells, a single `||` on a line is needed.
Example:
{{{
{{{
#!th
- some header
}}}
{{{
#!th
- another header
- with more rows
}}}
||
{{{
#!td rowspan=2
Arbitrarily big content (even an embedded table of course):
|| A || B ||
}}}
{{{
#!td
Second cell, first row
}}}
||
{{{
#!td
Second cell, second row...
}}}
}}}
