The eldrazi were introduced to Magic in Rise of the Eldrazi MTG set and have since returned mainly in the Battle for Zendikar block, in Modern Horizons 3 , in the Commander precons, Eldrazi Unbound and Eldrazi Incursion
You can only use 1 ""Infernoble Arms - Durendal"" effect per turn, and only once that turn
Using this card as a way to push through lethal might be a better plan than trying to attack each turn forcing blocks
Once you start targeting your creatures with single-target spells, that is when Frontline Heroism ramps up
Two mana is incredibly cheap for an effect like this, and the lack of any kind of once per turn limit makes Sram a serious powerhouse in the right deck
(For example, consider Vikavolt V, which was out of the spotlight for a long time before finally becoming playable again due to shifts in the metagame.) Finally, note that this is my top ten, so there will be some subjectivity involved