Tigris

Drei is one of the twelve Dark Warlords.

In Fire Emblem: Seisen no Keifu, little is said about the Dark Warlords, but they are all fought in the Final Chapter near Barhara and eventually defeated, including Drei.

In Fire Emblem: Thracia 776, Drei is fought in the Final Chapter. The character that becomes Drei is Dagdar if Chapter 8x is skipped.

Like all of the other Dark Warlords, Drei's name is a German Number, in this case it is three.

Seisen no Keifu
Axe Users in this game fail sadly due to the massive weight of axes and the fact their weight directly decreases axe user's attack speed by the weight of the axe, and the same can be said for Drei. Kill him off with Lakche or Skasaher since both use swords and swords beats axes, and their Awareness skill nullifies Drei's Wrath skill, or just kill him at a range.

Base Stats
|Warrior |None |30 |80 |24 |13 |18 |25 |4 |23 |16 |6 |0 |3000 |Pursuit Wrath |Axe - A Bow - B |Silver Axe

Thracia 776
Drei is one of the weakest of the six Dark Warlords in the Final Chapter. He has no skills, and his attack speed of 11 means that he likely won't be doubling many, if any, of your own units. Just be cautious of the Master Axe's 1~2 range, and Drei will be easy to defeat.

Stats
|Warrior |20 |46 |17 |4 |14 |11 |5 |13 |18 |10 |0 |4 |4 | - |Axe - A Bow - A |Master Axe