Protestant apologist Jason Engwer (words in blue henceforth) stated on 5-28-15:
[T]he evidence suggests that prayer to the dead wasn’t practiced by believers in the Biblical era, is sometimes contradicted by the Biblical authors, and was rejected in the earliest generations of patristic Christianity.
And earlier on 6-9-08:
The evidence from the earliest patristic sources is against the practice as well. Tertullian, Origen, and Cyprian wrote treatises on the subject of prayer without encouraging prayers to the dead. Instead, they either state or imply that prayer is to be offered only to God. Origen in particular is emphatic on the point (Against Celsus, 5:4-5, 5:11, 8:26; On Prayer, 10).
I’d like to take a look at Origen (c. 184 – c. 253) — his words will be in green –, what he stated, and whether it is consistent with Jason’s take or the Catholic one (i.e., such things were widely taught by the fathers).
For we indeed acknowledge that angels are
ministering spirits, and we say that
they are sent forth to minister for them who shall be heirs of salvation; and that they ascend, bearing the supplications of men, to the purest of the heavenly places in the universe, or even to supercelestial regions purer still; and that they come down from these, conveying to each one, according to his deserts, something enjoined by God to be conferred by them upon those who are to be the recipients of His benefits. . . . For every prayer, and supplication, and intercession, and thanksgiving, is to be sent up to the Supreme God through the High Priest, who is above all the angels, the living Word and God. And to the Word Himself shall we also pray and make intercessions, and offer thanksgivings and supplications to Him, if we have the capacity of distinguishing between the proper use and abuse of prayer.
For to invoke angels without having obtained a knowledge of their nature greater than is possessed by men, would be contrary to reason. But, conformably to our hypothesis, let this knowledge of them, which is something wonderful and mysterious, be obtained. Then this knowledge, making known to us their nature, and the offices to which they are severally appointed, will not permit us to pray with confidence to any other than to the Supreme God, who is sufficient for all things, and that through our Saviour the Son of God, who is the Word, and Wisdom, and Truth, and everything else which the writings of God’s prophets and the apostles of Jesus entitle Him. And it is enough to secure that the holy angels of God be propitious to us, and that they do all things on our behalf, that our disposition of mind towards God should imitate as far as it is within the power of human nature the example of these holy angels, who again follow the example of their God; . . . (Contra Celsum, V, 4-5; my bolding and italics)
Two things are going on here, that are complementary, not contradictory; “both/and” and not “either/or”:
1) Prayers ultimately go to God Who decides how He wants to address them: by granting or refusing the request.
2) Angels, saints, and fellow human beings (whether alive on the earth or inhabiting the next world) may intercede and present our requests, prayers, supplications, petitions to God on our behalf.
Origen (unlike many if not most Protestants) sees no contradiction or disharmony or discord at all between #1 and #2, and so he expresses both, casually assuming that both things are simultaneously true. Remember, this is one of the passages that Jason sent his readers to, to establish that Origen supposedly takes a “Protestant” view of the intercession of saints and angels. It turns out (what a shock!) that he is thoroughly Catholic.
The bolded parts of the above citation show that Origen believes that angels intercede for us to God. The italicized parts show that God is the ultimate recipient and granter or denier of the wishes expressed in prayers. Both things are true and in harmony. The key phrase relating to angelic intercession here is “bearing the supplications of men.” Supplications are prayers. The English word appears six times in the RSV in the New Testament, and its meaning is apparent:
Ephesians 6:18 (RSV) Pray at all times in the Spirit, with all prayer and supplication. To that end keep alert with all perseverance, making supplication for all the saints,
Philippians 4:6 Have no anxiety about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God.
1 Timothy 2:1 First of all, then, I urge that supplications, prayers, intercessions, and thanksgivings be made for all men,
1 Timothy 5:5 She who is a real widow, and is left all alone, has set her hope on God and continues in supplications and prayers night and day;
Hebrews 5:7 In the days of his flesh, Jesus offered up prayers and supplications, with loud cries and tears, to him who was able to save him from death, and he was heard for his godly fear.
So what are these angels doing when they are described by Origen as “bearing the supplications of men”? They are obviously interceding for them to God, ascending to the “supercelestial regions” where God dwells, and “conveying” to human beings “something enjoined by God to be conferred.” They are not only involved in the prayer to God but also in its fulfillment from God.
I think the angels described here are doing precisely what we see in the following passage:
Revelation 8:3-4 And another angel came and stood at the altar with a golden censer; and he was given much incense to mingle with the prayers of all the saints upon the golden altar before the throne;  and the smoke of the incense rose with the prayers of the saints from the hand of the angel before God.
In another post from Jason (6-9-08), he notes that such prayers “go to God.” Indeed they do (no one denies it):
Revelation 8:4 . . . refers to the prayers going to God. . . .
It seems that the best explanation of the prayers in Revelation 5 and Revelation 8 is that they’re prayers to God, asking for justice on earth. They aren’t prayers to the dead.
But of course he misses the entire point. These angels and dead saints (as in Revelation 5) are somehow involved in the process of these prayers “getting to God.” That’s precisely the intercession of the saints and angels. Why is that? How is that? If prayer is supposed to be solely between a Christian believer and his or her God, with no intermediary, why do “the prayers of the saints” rise to God “from the hand of the angel”? Likewise, what are the “elders” (usually taken to be dead men) doing with “the prayers of the saints” (Rev 5:8)? Why are they involved at all?
We don’t know what Jason would say about that because he ignores it (as he habitually does when he has no plausible alternative to traditional Catholic and biblical claims). But it’s pretty clear that this is what Origen taught in the above passage; therefore, he does not serve as a witness to Jason’s anti-traditional Protestant agenda as to the intercession of saints and angels. Nice try, but no cigar; e for effort . . .
So let’s see what his other alleged “prooftexts” from Origen teach us:
[W]e judge it improper to pray to those beings who themselves offer up prayers (to God), seeing even they themselves would prefer that we should send up our requests to the God to whom they pray, rather than send them downwards to themselves, or apportion our power of prayer between God and them. (Contra Celsum, V, 11)
[O]ur duty is to pray to the Most High God alone, and to the Only-begotten, the First-born of the whole creation, and to ask Him as our High Priest to present the prayers which ascend to Him from us, to His God and our God, to His Father and the Father of those who direct their lives according to His word. (Contra Celsum, VIII, 26)
In other words, we don’t pray to angels and saints as if they were the ones who granted or denied our prayers, and had the power to do so (the ultimate recipients). No one disagrees with that. The very terms Catholics use presuppose this: intercession of the saints (not, “saints granting prayers”): just as we intercede for each other on the earth. That’s our usual term.
It’s Protestants who always want to call it “prayer to the saints” or “prayer to the dead.” “Prayer for the dead” is proper. We do do that. But in any event, it is praying to God when we ask a holy person or an angel to pray for us. We ask them to pray, and they intercede to God on our behalf. Therefore, Origen saying the above things, and Jason citing them, does not refute Catholic practice. Origen’s thoughts in Contra Celsum V, 4-5 show that the two are compatible, in his thought, and logically.
Origen’s On Prayer (section X) offers much of the same thoughts expressed in the previous two excerpt. It can be read online. Again, the Catholic responds by saying that we ask saints to intercede and pray for us: not to answer our prayers themselves. It’s sort of like asking a friend who is in the right spot to “intercede” and speak on our behalf with regard to obtaining some job. Then if we get it we may thank them by saying, “you got me the job!” In a sense they did, but of course, ultimately, it was the employer who decided.
Catholics invoke saints and ask them to intercede for us for two reasons:
1) They are more alive than we are and certainly more spiritually powerful.
2) James 5:14-18 Is any among you sick? Let him call for the elders of the church, and let them pray over him, anointing him with oil in the name of the Lord;  and the prayer of faith will save the sick man, and the Lord will raise him up; and if he has committed sins, he will be forgiven.  Therefore confess your sins to one another, and pray for one another, that you may be healed. The prayer of a righteous man has great power in its effects.  Eli’jah was a man of like nature with ourselves and he prayed fervently that it might not rain, and for three years and six months it did not rain on the earth.  Then he prayed again and the heaven gave rain, and the earth brought forth its fruit.
Origen, in his most well-known work, Contra Celsum, explicitly endorses the notion of saints and angels praying for and with us (strongly implying also our invocation of them), in Book VIII, 64:
There is therefore One whose favour we should seek, and to whom we ought to pray that He would be gracious to us — the Most High God, whose favour is gained by piety and the practice of every virtue. And if he would have us to seek the favour of others after the Most High God, let him consider that, as the motion of the shadow follows that of the body which casts it, so in like manner it follows, that when we have the favour of God, we have also the good-will of all angels and spirits who are friends of God. For they know who are worthy of the divine approval, and they are not only well disposed to them, but they co-operate with them in their endeavours to please God: they seek His favour on their behalf; with their prayers they join their own prayers and intercessions for them. We may indeed boldly say, that men who aspire after better things have, when they pray to God, tens of thousands of sacred powers upon their side. These, even when not asked, pray with them, they bring succour to our mortal race, and if I may so say, take up arms alongside of it: for they see demons warring and fighting most keenly against the salvation of those who devote themselves to God, . . . (my bolding)
Note, especially, how Origen casually states: “These [departed saints and angels], even when not asked, pray with them . . .” The use of “even” shows that Origen assumes that it is also the case that they pray for us when asked; i.e., invoked. So there we have it. Origen is no Protestant, and teaches just as the Catholic Church does in this matter.