συνεισβάλλειν

From LSJ

ἀλλ' οὐδὲν δεῖ παρὰ τὸν βωμόν σε βουλεύειν → better safe than sorry

Source

Greek > English (Woodhouse Verbs Reversed)

(see also: συνεισβάλλω) help to attack, join in invading