Combos Utilizing Quillspike

Tap Devoted Druid to add mana, untap and add the -1/-1 counter, use mana and counter to give Quillspike +3/+3, repeat indefinitely. Obviously easily blocked, so throw in a trample card like Primal Rage for good measure

tap druid for mana, untap, use mana and remove counter to give Quillspike +3/+3, infinite combo. Obviously easily blockable so pick anything giving you trample (I use Primal Rage)

Load the Quillspike up with 3 -1/-1 counters, then remove them all to get a very large combatant.

Well here is the famous combo of redcap+quillspike+phyrexian altar i take no credits from that part but i tought why not adding a another annoying card to stop ur opponent from destroying u a creature with an ability if u thinking of doing a deck with these cards try adding "Flourishing Defenses", "Soul Snuffers", "Fate Transfer" and "Crumbling Ashes", i'm currently working on a new deck so if u find any related cards with -1/-1 counters or stuff like that