Ofc, i put it there cause that slow, and 125% extra dmg, and the much needed 70 armor, gives you a good defense bar, put, doin well. go for trinity any day of the week. I put it in core, so people give it a try, and let me know how it went:) But, i have to change this guide again.

Just wondering why you put iceborn in the core slot
Trinity is 500 more gold, and as i see it, the AP on iceborn is close to useless, the mana completely useless, the slow is nice tho, but i'd rather pay 500 gold extra to gain attack speed, movement speed, HP, 200% base dmg proc (instead of 125%), Crit & attack damage - You do loose out on some armor tho, but i still find it "generally" a better choice