I run armor yellows, armor pen reds, scaling mr blues, and ms quints. For mastieries, i go 9-18-3 grabbin 3 in meditation.
Start machete and pots. Then get apirit stone and boots of mobility. Upgarde the spirit stone to ancient golem for tankiness and tenacity. From there you need to decide whether or not you need to build full tank or a bruiser depending on what your team needs.
J4's ganks are very very strong especially with the mobility boots. Use you e->q combo and waot for them to burn flash. Once thet use flash, dunk them with cataclysm. --- xbox live gt: Tweekerlime