"Doer of wonders" (Exodus 15:11). It is not written here "He did a wonder," but "doer of wonders" [in the present tense], referring to the time to come, as it is said, "Therefore, behold, days are coming, says the LORD, when it shall no longer be said, As the LORD lives who brought up [the children of Israel out of the land of Egypt]" and so forth (Jeremiah 16:14).
Doer of Wonders in the Present Tense Points to the Days to Come
Yalkut Shimoni on Torah 250:5
עֹשֵׂה פֶלֶא. עָשָׂה פֶלֶא אֵין כְּתִיב כָּאן אֶלָּא עֹשֵׂה פֶלֶא, לֶעָתִיד לָבֹא, שֶׁנֶּאֱמַר "לָכֵן הִנֵּה יָמִים בָּאִים נְאֻם ה' וְלֹא יֵאָמֵר עוֹד חַי ה' אֲשֶׁר הֶעֱלָה" וְגוֹ'.