As it costs at least seven mana you have to replace top end with it rather than mid level cards and that makes your deck significantly less threat dense
For example, if one player has 10 life and the other has 17 life, the first player gains 7 life and the other one loses 7 life
Theyre great to cast at a discount, great to exile to make a bunch of tokens, and fantastic with a bunch of tokens in play since you can use them to get a bunch of extra combat steps to attack a player down
Enchantment Creature - Human Soldier
In Izzet, that MIGHT also be extra damage, of course, and youll have no shortage of Wizards, Giants, and big damage spells
Anything that has synergy with other Eldrazi creatures to put them into play faster or make them indestructible will instantly win you the game