Even if this was just doubling your team it's really good, but when you consider all of the ETB's that are in the average deck you see the true potential
Note that activated ability does cost 8 mana, so that's pretty pricey, but that's not an issue in the infinite mana you'll have in Type Four, although a 4/3, with trample and reach is pretty small, even if you do get it twice
, , Pay 1 life: Create a 1/1 white and black Human Cleric creature token
Doubling your lifegain just doesnt matter in Limited, and cost reduction isnt that important either, especially once youve hit 4+ mana already
If they are interested in buying, they will most probably pay you less than the cards are worth