$table
->setRows([
[
new TableCell('1', ['colspan' => 2]),
new TableCell('2', ['colspan' => 2]),
new TableCell('3', ['colspan' => 2]),
new TableCell('4', ['colspan' => 2])
]
])
->render()
;
+--+--+--+--+--+--+--+--+
| 1 | 2 | 3 | |
+--+--+--+--+--+--+--+--+